What Does A Painful Patch Of Fat Near The Tailbone Indicate?

Hello I have a patch of fat near the tailbone area, and it hurts anytime I try to do sit up or lay flat on it. Recently, I've lost some weight but that patch of fat is protruding. It doesn't hurt when I touch it, there's no head like a pimple either. I'm a little concerned because my cousin who was 17 had similar symptoms and she went to ER and they lanced and her blood level dropped and they found amount that she had ASL Leukemia which she died less than 3 weeks after being diagnosed. I'm 43, 5'8" and no medical issues that I'm aware of at this time.