Bactrim Cold Sweats, Severe Headaches, Allergic to Sulfa Drugs, Benadryl, Stiff Neck

I can't believe I am reading about the same thing I am going through..it helps me to know it's not just me. On Day 7 of bactrim I started getting joint pain but never linked it to the medicine, I figured I was getting the flu or a virus. On day 9, about 30 minutes after my morning bactrim dose, I broke out in a rashe that looked like measles or chicken pox all over my back and chest. I immediately knew it had to be an allergy to the medication (I am a nurse) so I took 50 mg of benadryl and discontinued the med, thinking that would take care of it. Wrong. That night I was in the ED with stiff neck and severe headaches and worse hives all over my body. I went home on benadryl; no one mentioned prednisone, they seemed to think that all of my symptoms except the rash were related to being dehydrated, although they also said, oh yes you're allergic to sulfa drugs. Last night (Sunday) I had to change my clothes twice waking up in cold sweats that soaked through my pajamas to my sheets. I've had chills. Tonight I can't sleep with even worse itching. I haven't taken a bactrim since Saturday morning and it's Monday at 4:00 AM. My hives are worse, if anything, although at times they look better and I get excited, but they come back. I'm at my wit's end hoping this stops soon. I will NEVER take sulfa drugs again or allow my children to take them.