Hi, i have a boil under my armpit, i've stopped shaving and changed my deodorant, taken antibiotics. the boil has been here for 3 weeks now and the pain has migrated down to my entire right arm. also feel alot of heat and pain in my right arm.

You have an: abscess by your description and a fairly well established one at that. Antibiotics can only partially contain this and will not resolve an abscess. I am sorry to say you are going to need this incised and drained as soon as you can. If you know a good general surgeon call him/her or your PCP for a referral. Failing that a good Emergency department can perform. Don't wait too long