You should go see a dermatologist. If you just leave the boil without special treatment, it will most likely get worse. The doctor might need to burn it off or give you a special prescription strength cream. I have also heard of using bacon fat as a home remedy. In this case you would put the fat on the boil and cover it with a band aid to heal overnight. Still, I would recommend seeing a doctor so that you don't end up with an unsightly hole in your thigh! Good luck.