I just got bactrim prescribed to me when I had to go to the emerg...

I just got bactrim prescribed to me when I had to go to the emergency room a few nights ago for an extremely high fever. They found it was a UTI and Kidney Infection. I started taking bactrim Wednesday morning and almost right away I started developing a headache. About an hour after it had begun, it turned into the most painful, throbbing headache I have ever experienced in my life. It does not go away at all. I have literally had it since Wednesday, all day, all night. Finally I called my doctor today and they said they had "no idea" why I was experiencing these problems. I told them that it started almost immediately after starting to take this medication and I was simply told that "antibiotics don't cause headaches". I beg to differ!!! I'm on day three, four more to go. I honestly can't stand this. It's interfering with my whole life. I would avoid this antibiotic if possible.