What Causes Rashes On Body And Headaches After Taking Penicillin?

Hi. I had tonsillitis last week which was cleared with penicillin, and a few days ago I brokeout into a rash which only lasted a day. I have been getting headaches to. I had unprotected sex about a month ago and I m very stressed thinking I have hiv. Could I possibly be making myself sick causingme to eexperience these symptoms