Was prescribed this 9 days ago for a sinus infection. Last night...

Was prescribed this 9 days ago for a sinus infection. Last night (the 9th day) I was getting ready for bed and noticed a rash on my arm. I then noticed that it was on my other arm...and then saw it on my legs, chest, abdomen, back, etc. Basically everywhere except my face (though today it has shown up slightly on my face). After noticing the rash, I took some Benadryl and went to bed. About 30 minutes later I woke up suddenly--I felt a bit woozy and dizzy. Suddenly, my legs started jerking, my body was shaking, teeth chattering etc. My husband called the doc on call, who said that the rash was definitely due to the antibiotic, and that the dizziness/lightheadedness was most likely a reaction to the Benadryl. She said the rash would probably last about 3 days, and that as long as my breathing stayed fine and my lips/tongue didn't start to tingle, I would be OK. It has now been almost 24 hours; the rash is still there and I have had chills off and on throughout the day. The doc called to check on me a few minutes ago, and told me if the rash is not improving by tomorrow (Monday), to come in to the office. She explained that she was a bit concerned that the dizziness might be low blood pressure resulting from the reaction to the sulfamethoxazole, and that it could make a person very sick. She wasn't as concerned since I hadn't experienced the dizziness again since. Scary!