A Couple Of Weeks Ago I Had A Cold Sore

A couple of weeks ago I had a cold sore on my lip and my lips were (are) very dry. Then I had a swollen right eye and both eyes were red and watery. Then I started to get a rash on my right arm and on my upper thighs. I went to the doctor and they diagnosed the swollen eye as having a sty and prescribed Amoxycillen. They asked me a bunch of questions about any possible allergies. I stated I did not consume anything different nor did I take any new medications. They did not know what it was and told me to take Benadryl and dismissed me. My sty soon went away but the rash got worse and worse ever since. I went back to the doctor this past Tuesday and they took a skin biopsy and I am awaiting the results. They gave me Prednisone but it has done nothing for me. The Benadryl did not help with itching so I switched to Zyrtec, which has helped somewhat. My rash is basically over my entire body. It's gotten dark and angry looking and in some areas it looks like I have sunburn. Some of the skin is starting to peel. Any idea what this could be.