I have a rash under armpits, down arm, and inside thigh. It itches really bad. Could this be shingles, any home remedies? I'm 33

Not shingles. Shingles is almost exclusively only on one side of the body and it tends to be painful. More likely is an allergy to something that is coming in contact with the areas you mentioned e.g. Soap, body creams or lotions.