Severe Allergic Reaction to Bactrim - Need Advice

hi, i have had what the pharmacist calls a severe allergic reaction to bactrim after only seven days on the medication. i have had lymph node swelling, a rash on my abdomen that later spread up through my neck and down my arms, severe abdominal cramps, nausea, dizziness, insomnia, abdominal bloating and swelling, and other general pain and discomfort. when i went to see a nurse practitioner, she said she didn’t think it was an allergic reaction, since it had been about a week. i did read that it can take a week or so to show an allergic reaction. has anyone had anything similar? there is really no other way to describe the symptoms i’m experiencing, and the doctor ruled out several possibilities, but really still has no idea of what is happening