What Could Large, Hard Protuberance Around The Crease Of Public Area Indicate?

I am a female, 71 years old. On Christmas Eve, after going to bed, I suddenly discovered a large, rock-hard protuberance just where the top of my thigh and upper edge of pubic area join--at the crease-on the righthand side. It is still there. It does not hurt and is not sore or tender, and is colored just like the rest of the surrounding skin. It feels like a large walnut or small golf ball in size and will not palpate or budge at all. Just feels like a big, rounded bone that was not there before, and there is nothing corresponding to it on the left side. In the past, I have known two people who suddenly had the same kind of large, hard lump appear overnight. A woman I knew had this appear on the top of her head. My husband had one appear in the pit under his right arm, overnight. Both of them died of cancer within six months after the lump(s) had appeared. What do you think?