Red itchy circle on chest getting bigger and bigger what could it be?

Ring worm: This could be ring worm tinea corporis It could be a fungal infection (yeast infection). Would need to see your primary care provider to confirm.

Likely ringworm : Tinea corporus is very common and should resolve with over the counter clotrimazole 1% cream twice a day. If the rash doesn't start improving quickly, go to a doctor for evaluation and treatment. If the cream does work, make sure to continue use it a few weeks beyond when the rash is not visible as the fungus can still be present.