Medication - I had been taking Naproxen for the last 4 months (2tabs/day) and recently developed?

Anytime you experience anything new with your medication that you didn't have before, you should contact your doctor. It may be a side effect from the meds but they need to know. Your doctor may adjust your dose.
Depending where your back pain is there could be something else going on. For example if its lower mid back it could be a kidney infection and you could get s urine test yo find out. I've had kidney stones and I thought my back was going to explode.

So its worth your time to call your doctor
Good luck
Jen

Hi junolane, & welcome to the site. Back pain is not a usual sign of anything to do with naproxen. Usually it can bother the stomach with burning & irritation. I would suspect you could be having back pain due more to having plantar fascitiis by not walking correctly due to pain. It can really throw your muscles out of whack. I have had this too, & it's a very painful condition. Do you know the exercises to do for this condition? You can probably find them on Webmd. If not then I would see your doctor about getting a referral to physical therapy to help you get through this. Be sure to do some feet stretching before you get out of bed in the morning. It will help before your feet hit the floor for sure. You really need to be doing the correct exercises for this. If it goes on too long you may have to have special insert made for your shoes. You can buy the Dr. Schols insert which will help you some, but the exercises are the most important part. Hope this helped you a bit...