I had an infection on my foot (could have been Staph because it w...

I had an infection on my foot (could have been Staph because it was very aggressive and painful with lots of swelling) and was prescribed 'Bactrim' or Sulfamethoxazole. Everything was fine for the first 8 days. My infected foot was healing. On the 9th day, I developed a rash that I noticed first on my wrist and then my neck, inner thighs and my feet. I went to the doctor who said to not take my 10th and final day of Sulfamethoxazole and prescribed benadryl. Later the same day (tonight), the rash has spread everywhere from face to toe. The itching hasn't been severe but it has been uncomfortable, sort of like mild pin pricks in random places on my body. I'm going back to the doctor's office tomorrow since they told me to expect it to get a lot better by tomorrow. I'd be surprised if it gets better but it definitely has gotten worse.