I Fell Down Seven Stairs And My Butt Took The

I fell down seven stairs and my butt took the worst of the fall. There's a massive black bruise on it which has came out on a lump. It's the rest of my bum cheek that hurts. It's swollen but no bruise on the really painful part and it kills me to even turn in bed or go from sitting to standing. Is it just internal bruising