Suggest Treatment For A Painful Bump On The Armpit

i have a painful bump under my right armpit. i had it for about 3 days now and my mom say its a hair bump. i put a hot washcloth on it n its stop hurting and even go down a little bit but then it come back to its normal size a few minutes later.what is wrong with me. i wanna go to the doc but my mom say its not that serious.