Itchy Skin Rash. Taking Diazepam. Have Neck And Back Surgery. Want Medicine

I recently developed a skin rash that where the itching is severe. I suffer allergic reactions to new medications or taking a prescribed med more often. I am very allergic to cortisone and steroids. The only new med I take is Diazapam 10 mg. I take it for nerve ending flare ups from Fibromyalgia . Also, I have had six neck and back surgeries since 2004. The Diazapam really works. I was given one tablet three times a day. At first, I only took them one a day or at varied flare ups, but they worked so weak I took three/day. Reading side effects, itching was a side effects. I use topical creams, they didn t work long. Benadryl works well, would like to use something long acting without the drowsiness. Thank you.