i've had this for couple months now too. Midwife reckons i've had a fall and landed on my butt (which has happened uncountable times thoughout my life) and broken my tailbone without realising it. It's extremely and i mean EXTREMELY painful in everything i do! I've tried cushions and pillows, sitting in forwards positions and leaning backwards positions. I've tried the stupid doughnut pillow the doctor swore by. Nothing works sadly. If you find anything let me know! Good luck!