What Causes Skin Rash And Neck Pain After Using Penicillin?

about one month ago, I was diagnosed with strep throat. Began a course of penicillin and within a few days was covered in a rash (that remains). Saw my dermatologist who said it was a reaction to penicillin. (Stopped penicillin). About one week later woke up in the middle of the night with neck pain on my left side. Didn t think much of it initially, but it s become progressively worse. Saw my GP - prescribed muscle relaxants and neproxine. Pain kept getting progressively worse - both sides of my neck into my head. Called the doctor fie days after my initial visit, he suggested emergency if it was not better. Woke up again the the next day agin with terrible pain (was up most of the night as I had been). Went to emerge - blood results and CT of my neck normal. As a note, my period began and has since stopped within three days. Left the hospital with additional muscle relaxants and ativan. Background: i have ulcerative colitis, and sacrialitis and am on remcade infusions every six weeks. I would welcome any insights...just not recovering as i would have expected.