For the last week, I've had a growing lump in my right buttock. It's near where my glute meets the back of my outer thigh. It only feels sore when I sit for too long because of the pressure. You can barely see it from the outside, aside from slight pinkness. It's not getting smaller and I can't sit properly - feels like sitting on a wallet. Is it a cyst? I get those from time to time, but this one is the size of a golf ball and getting bigger.