Lump On Buttocks Crack, Leg Pain, Trouble Walking. Stomach Pain, Temperature Sensitive. Related Symptoms?

I just noticed a lump at the top of my buttcrack a few weeks ago. Prior to noticing this I had been experiencing pretty extreme leg pains. Been having trouble walking sometimes and cannot move faster than a slow jog. Anything past that is excrutiating. I played football for many years and Id like to think that Im a tough man, but this kind of pain almost drops me to the floor. If I walk carefully and dont try to bother it I can usually keep it at least somewhat subdued. Im a little worried about it. Also, not sure if its related to this bump, but Ive been having odd stomach pains; seems like im hungry almost, but a little more painful than that. Other than that, Ive been a little temperature sensative.