Does anyone know what this rash on my baby is?

My 6 month old has a rash, it’s below his chin. he is pretty chubby and we often have to clean his neck so it doesn’t get a rash but this is closer to his chest than his neck so I’m not sure if it’s related. I’m super paranoid about him getting sick so I could be overreacting. I just didn’t want to call the doctor if it was nothing. Thank you if u can help