What Causes An Excessive Burning Sensation In The Buttocks?

yes when I sit down my butt, back of legs, tailbone, and up my tailbone around my waist in the back burns like its on fire and when underwear pants or shirt rub it burns plus the more I sweat or get in a warm room it flares up what could it be????my mom checked my butt and back of legs and they look 100 percent normal...I pressed all over my legs my butt and my tailbone and the most spot was my tailbone and my sides a little and above my tallbone a little