Rash on base of neck, inside of arm below armpit and side of chest

I have a rash I started devoloping 3 days ago. It seemed to worsen after one day and then stay the same today. I have a rash about 3 inches long and 2 inches wide at the base of my neck on both the left and right side. Also on the left and right side of my torso just below the armpit about 5 inches around, and on the inside of my left and right below the armpit 3 inches long and 2 inches wide and half that size on the left arm. It is a light shade of red and was bright red when I got out of the shower It itches quite intensly and itches even worse when I scratch it. It is also bumpy. There is no pus or infection, at least not yet. I try to leave it alone as much as possible.
Thanks for the help.

[Alan Rockoff, MD]

I'm not sure, but these could be hives.  Hives can be allergic (a new medicine, for instance), but are most often triggered by nothing in particular.  Soaps and detergents rarely play any role.  I suggest that you make an appointment with a dermatologist, but meantime, apply an over-the-counter itch lotion containing menthol (ask the druggist) and try taking an antihistamine like diphenhydramine 25 milligrams at bedtime (also over-the-counter.)  Don't be surprised if the rash appears elsewhere before it goes away as mysteriously as it came.  But only someone who sees it can tell you definitively.

Best.

Dr. Rockoff