I have this lump a little underneath my left buttocks/ at the very top of my upper left leg. It's been there for a few months now. I've noticed around the middle of summer this year. It's a little painful when you apply pressure to it. It also seemed to had gone away at on point towards the end of summer but I'm noticing it again. 



I'm pretty worried as to what this might be. I haven't seen my doctor yet but I feel I should soon.