http://www.medications.com/effect/view/37461 I'm on bactrim for a kidney infection. The first day I was fine. I was in so much pain, after 2-3 pills it made me feel a lot better, I'm taking bactrim 2x a day for 7 days. I'm on day 4 and feel like crap. My backache is back, headache, cramping, stomach a Mon, 05 Jan 2009 16:09:11 -0500 http://www.medications.com/effect/view/37461?item=15735 Hi, I had severe backache from this stuff too. Can you explain when your backache went away my has gotten better (I am now on day 2 of not taking Bactrim) but, I still have a hard time sitting in the same postion for a long period of time. My pain is right http://www.medications.com/effect/view/37461?item=15735