I have a strange lump that is on the inside of my upper thigh. It is darker in color and very hard. At first, a few weeks ago, it did not hurt and was very round, and the size of a marble. I used some drawing salve on it (my mother believed it was a boil) and it receded into my leg. A few days ago it came back up, and is causing me a lot of pain when it is pressed upon or if I remotely brush against it. It also has the tendency to change shape, I am using the salve again and I just removed the bandaids to find it has become more oblong and feels a bit larger.

I was wondering if anyone thinks this is serious at all or what it could be?