For the last 8 days my skin is itching all over - when/if i scratch the entire area becomes red. i also have one boil on my penis? i have been taking generic claritin for the last 5 days. i don't have dry skin, but have started applying cetaphil?

As you can imagine a medical opinion requires detailed information and a proper evaluation. This forum is designed for general health questions, not specific health advice. Your concern needs an in-person examination

Your skin is very reactive & probably sensitized by some substance ingested or that came in contact with your skin. When you rub your skin,histamine& other chemicals are released causing welt like redness& itching ( dermatographism). Claritin or benadryl may relieve this allergic reaction.but you may need more help from an allergist. I'd stop applying cetaphil until you see the allergist.