Is Bactrim DS safe to use for UTI's? Worried about side effects!

[Healthsavvy]

After having a burning sensation when I pre and irritation. In my vaginal area inside my urethra, I recently discovered that I have a UTI and was prescribed the drug Bactrim. I am suppose to take it twice a day for 3 days. Anyway, I have a history of being allergic to antibiotics and getting the "rare" side effects. I was reading the side effects of Bactrim and I am horrified and super worried! I don't react very well to antibiotics. I asked my doctor if he could prescribe me a different drug, but he said no as the others on the market are more for complex UTI's and since mine is still in the mild phase it's the only and safest one he can give me. He even moved me from 10 days of being on it to just 3. I'm sacred mostly of the possibility of "Steven Johnson Syndrome" since I've broken out in a rash/ hives in the past on antibiotics. Usually it was within the space of 4-5 days on the drug and when I had to take them frequently. I don't want to die and I don't want my skin to peel off or have other issues. What do I do? He said the FDA now wants doctors to regulate Cipro so he can't prescribe that and the side effects are much worse he claims. Why are pharmaceutical companies putting horrible drugs on the market? I have sensitive skin and worry about that issue. I've never taken this drug before.