My Son Has A Burgundy Red Patch On His Hand

My son has a burgundy red patch on his hand that occurred after he wore rubber gloves where he works as an auto technician. He was sweating profusely (the garage is not air-conditioned) and his hand started to sting, but he kept the glove on due to project deadlines. No he has had this patch for a week (a few small blisters) and it has not changed. Info and treatment advice would be appreciated.