Can you switch antibiotics in the middle of a course?

Yes you do have to take the full course. They work differently and you should follow the drs instructions.

You always want to finish the whole course of antibiotics whenever you are prescribed an antibiotic, because even if you skip the last one or two doses of your antibiotic, the infection can possibly come back, and be even harder to treat, as the bacteria that you were trying to get rid of have now become desensitized to the antibiotic you were on to treat that infection, and you'll either have to take a greater dosage, for a longer period of time, or go on to another antibiotic that's perhaps stronger, and perhaps for a longer period of time. You'll want to finish taking your current antibiotics. You only have a few more days left, anyways. One of the reasons why there are new antibiotic-resistant strains of bacteria infections arising is because of people not finishing their whole course of antibiotics for one reason or another. This can cause bacteria to essentially become immune to the current antibiotics most commonly used to treat that specific strain of bacteria, making it more and more difficult to treat those strains of bacteria with our current antibiotics. This is part of the reason for the rise of such strains of bacterial infections such as MRSA (which I personally have plenty of experience with, and it's only treatable with 3 types of antibiotics, 2 of which I'm allergic to. I've had MRSA 3 times, and have a problem that causes me to get abscesses under my armpits, which is how I've gotten the 3 MRSA infections I've had so far, so if I ever get to the point where some time down the road I have another MRSA infection and the one antibiotic I can use no longer works for me to treat MRSA, I'm basically screwed) and treatment-resistant tuberculosis. The other main reasons of the rise of treatment-resistant bacterial infections are the over-prescribing of antibiotics (such as prescribing antibiotics for colds and other viral infections like the flu, which, of course, won't do one damn thing, and the only thing that will work for shortening the flu is an antiviral like Tamiflu.), as well as the everyday overuse of commonly-used antibacterial household products such as antibacterial handsoap, antibacterial bodywash and hand/body lotion (which I swear truly exists!), Purell hand sanitizer, Lysol, antibacterial wipes like the Clorox and Lysol wipes, etc. In reality, the only times people should be using such products in regular, day to day life (barring working in such industries like the healthcare industry, food industry, and jobs where you're working with a large volume of people daily, as well as handling a good deal of cash, because money is DIRTY, LOL! But I'm specifically speaking everyday home usage) is after using the bathroom when having a bowel movement (in reality, urine, if you're healthy, is actually sterile until it hits something, once it leaves the body, that contains bacteria), after handling raw meat, if you're sick and blow your nose, sneeze in your hands, etc., to prevent spreading your illness to others, and in reality, not much else. Regular, plain old soap and water is suffice for cleansing your hands and body in most situations, as long as you wash your hands properly, washing for at least 30-45 seconds with the soap lathered on your hands. The overuse of antibacterial products for just about everything has contributed to the cause of strains of treatment-resistant bacteria as well. When cleaning around the home and in the kitchen, simple soap and warm water will clean surfaces down just as well as antibacterial products, and products like Lysol/Clorox wipes should really only be used on kitchen counter tops and such only after raw meat and other raw products have made contact with the surface. Otherwise, it's truly overkill to clean those surfaces with antibacterial products. But anyways.
I suggest you finish taking your current antibiotic. It's only for a few more days. Is it possible for you to switch to formula for the rest of the time that you're taking it, just for a few more days? Do you have any breast milk stored in your fridge/freezer that you can possibly use until you finish your current course of antibiotics until you switch over to the next one? I know that there's also these breast milk... umm... don't really know what to call them, maybe donation centers? I know that there's this system where woman donate breast milk to these centers for women who need breast milk for their own children who can't lactate, or lactate enough to completely feed their children, and can't, or don't, use formula for one reason or another, and apparently it's kind of like a blood bank except for with breast milk, and as far as I know, they test the breast milk to make sure that there's no diseases or medications or whatever being passed on into the breast milk through the donating woman's body. Is there some type of center like that in the city where you live, or perhaps nearby, where you could possibly get some donated breastmilk to feed your child with for just long enough until you finish your current antibiotic course? If not, do you happen to currently have any female friends with young children who are currently still breastfeeding that you would trust enough that you would feel comfortable feeding your baby with their breastmilk, who you might think would be willing to express some extra breastmilk to help you out feeding your child for just a few days, that would be able to express enough breastmilk to do so? Or perhaps might already have some extra breastmilk already expressed and in the fridge, that you might think she would be willing to give to you? I know it might sound "gross" at first, but apparently this is a pretty widespread thing across the country among women who choose to breastfeed their children. And as far as I know, it's perfectly fine to feed your child breastmilk from another woman, as long as the woman the milk is from is healthy herself and not on any kind of medication that is expressed through breastmilk. I really hope that I have helped you in some respect.