Oh oh oh, I had this, it was terrible!!!!!!!!! And I am a chiropractor so it was like a bad joke...
Quick relief with this stretch:
sit at edge of bed or on a chair, both feet planted on the floor, sitting squarely on both "sit bones" in your butt
if stretching the right side, put your right ankle on your left knee
let the right knee drop outward as far as possible
lean (curl) forward as far as bump will allow you
you'll feel the stretch in your bum/ hip (sometimes also in inner thigh)
if bump too big to lean forward, start in same position
sit up very straight, even arch your back a little
lean forward, leading with your chest (well, bump, really)
you'll feel this a bit more intensely than curling forward
do both sides a couple of times
Good luck!! If this doesn't make sense let me know and I will post a pic on my profile.