I've had small medium-sized circles on my arms and legs for 2ish days. No past medical problems except a few broken bones no medication either.
Not a great photo, but could be urticaria. If they go away quickly - over a period of a day - then that probably what it is. If not, I recommend seeing a board certified dermatologist.
Could be a contact dermatitis (i.e., poison ivy). If itchy, apply hydrocortisone cream. If very itchy and spreading, visit your local dermatologist.
Stephen Schleicher, MD