What Causes Rashes Throughout The Body When Diagnosed With Pemphigus?

I went in to the emergency room one day with symptoms of the flu and sinusitis. They did cat scan. No sinusitis. They did test for meningitis. I didn t have it. But when I left ER they didn t know what was wrong with me... I had fever of 102.3 and they did blogs and urine test. Still nothing. They gave me amoxicillin. I developed a rash on my leg that same night before I left the hospital. They failed it was a reaction to medication. I had a follow up a few days later and they said it was cellulitis. They gave me bactrim. It didn t help. My leg developed blisters. I still had fever. I went back to same ER. They said I had pemphigus. They gave me clendimicin. Idk how you spell it. I finished that. I now h have a full body rash. What s wrong with me.