What can this rash be?

Tick bites can cause a circular rash. There is usually sign of the the tick. A small dark pinpoint may be a tick. If there is no dark pinpoint in the center, the tick is either gone or it is not a tick bite. It would be best for a physician to take a look to determine if it is a tick bite or something else..

Other possibilities are allergic reaction to food, drink, etc. Try to remember what you ate hours before you noticed the rash.

Itt could also be a staph infection. Clothing such as socks, shirts, uniforms, etc. should be cleaned and dried thoroughly. Keep the areas affected clean and dry.

Again, it would take a physician expertise to help you.

Psoriasis or candida. If it's been there over a year and it's not painful or itchy, I wouldn't freak out. He can try putting dandruff shampoo on it for 10 minutes a day. I went to the doctor repeatedly and they shrugged me off with no advice because I didn't hurt or itch and it stayed for years, only to find out from a customer at work that dandruff shampoo was the solution.

Could be all sorts of things. Probably ring worm (maybe) or as another user said, Lyme disease.

they look very circular.

do you or does he have a dog, cat??

could be ringworm, are they raised or is the skin just red??

it could be allergies but he needs to get it checked

My guess would be ringworm

psorisis