What Are The Side Effects Of Calvepen?

After taking calvepen for 5 days for tonsilities, I noticed a rash developing on my skin. It got worse, looks very similar to an amoxicillin rash and is all over my body. Went to see doctor, 4 days ago, he prescribed piritin and neo-claritin but I still have the rash. How long will it take to subside? I don't seem to have any other side effects? Also, I have taken calvepen twice before without getting this reaction. I'm a 24 year old male