I was prescribed sulfameth/trimethoprim 800/160 TABS for a kidney...

I was prescribed the Sulfameth/Trimethoprim 800/160 yesterday evening after i had cervical surgery. I went into the hospital for my surgery and I showed them a bite on my leg that I had gotten over night. The bite was very swollen and red about the size of baseball around with a little bite in the middle or it, It looked alot like a spider bite but we wasn't sure, the Dr seem to think it was the community staff you can get from bug bites sriders ect.... So the Dr's gave antibiotics threw my IV and sent me home with this BACTRIM. I personally have never heard of the medication but I took my first dose today the 12th of July about noon and it is about 9pm now the same night and it;s time for my next dose. The only problem is that I am feeling slightly out of it kinda in my own world, My appetite is gone completely I cant even swallow food, I am itching from my legs arms,back,chest face,and head very bad and It feels like chill bumps all over my body. I am very tired and can not seem to sleep. Can someone please help me out with this if you have any clue of what it could be or if i need to stop the med or not.

I was given Sulfameth/trimethoprim 800/160 tabs for a severe UTI infection. At that time I was so ill and pained from the UTI that I was not aware of any immediate effects. After taking this medicine for 5 days (2 tabs daily) I developed, What I thought, was a severe sinus headache. Any head movement caused intense pain. I even felt burning between my eyes. Any pressure on my eyelids was unbearable. For two days, I treted this as a sinus headache. However, I got little or norelief from the usual sinus remedies. In desperation, I 'max-dosed' myself with sinus meds. After two days of suffering, A light bulb went on in my head--maybe this could be the "headache" side effect! At that point, I had taken 15 of the 20 tabs. I stopped! 24 hours later, a rash appeared all over my body. I also have ugly red blotches that look like burns. Even though I stopped this medicine three days ago, I still have a slight headache and itch. It's like a curse that never stops. "BAD" medicine--"AWFUL" experience!!!!!