I have 2 red smooth quarter sized spots on my left backside upper arm and one red smooth spot on my right arm by my elbow what is it?

Tricky: dermatologic conditions are hard to discuss without seeing them. I go with the process occurrring (which could be infection or insect mediated) and the location to give clues. Bites, ringworm, even syphillis are possible. many other possibilities i Psoriasis if it has scaley parts is possible; eczema if itchy. Reactions if you've had an exposure at JUST those locations, but those seem less likely