Suggest Medication For Persistant Pain Due To Blister In Foot

I was walking one day then my foot started hurting really bad and i looked at it, this was about two months ago, and i noticed a small bump. I figured it was a blister and moved on, but it always hurts really bad especially when i walk. It is about the size of a dime now but is gradually growing. What is this bump? Is there anything I can do to get rid of the pain?