urinary tract infection
"After taking the 2nd dose, I began having a very bad burning feeling in my stomach. Then my back muscles hurt. The was no getting comfortable. I also could only urinate once in 10 hours when I had been going about every 2 hours prior. About 10 hours after I took that dose, I finally and unexpectedly vomited. I fell asleep for a few hours and when I woke, my backache was gone and I wasn't doubled over in pain from my stomach. I immediately decided that I wasn't even going to try another dose and called to be put on something different. It's now been 5 days since I took this medicine and my stomach still feels like it has a hole eaten through it."