I was on a Bactrim generic medication for a week, taking it twice a day although I missed a pill of it. I just stopped on Friday. I've been taking my bc (Emoquette) for about two weeks and it said after the first week of taking it that I am protected. Yesterday me and my partner had unprotected sex for the first time and I'm now worried that the antibiotics could have messed with the birth control. Should I take plan b? Will that mess up my birth control?