Penny size red circle on my upper arm, noticed it maybe two weeks ago at the gym. doesn't itch, not scaly, just a pink, slightly raised coin.

Need to see: Diagnosing skin lesions is almost impossible without seeing them. You need to see your family doctor to diagnose them or a dermatologist.

Ring Worm?: Tinea corporis (ring worm) often begins as a circular or oval, red, scaling patch. Usually has central clearing with an active advancing border a few millimeters wide. Lesion shaped like a ring. Responds to daily application of topical antifungals. Could also be an eczema patch which can be treated with topical moisturizers or hydrocortizone cream.