The gluteus maximus (bum muscle) is a sod when it get's wrenched because it is a big deep muscle making it harder to effectively boost the healing circulation to reduce the swelling therefore reduce the pain. Plus, rubbing your bum is embarrassing if you are caught doing it.
So on top of the above advice, try the tennis ball trick.....place a nice hard tennis ball between the painful bum cheek and a hard wall. Lean into it, move it round slowly. Has the effect of massaging deeper into the tissue.
And give it time, it will eventually go away. Not the tennis ball. The pain.