I could have posted this myself, my situation is so similar.  I have been battling SI/Hip pain for about 6 months with little or no improvment.  Been through, Chiro, rolling, lacross ball, acupuncture, Deep tisue massage, MWod/Supple Leopard,  rest, but it always comes back after a few days of lower body movements that involve squatting position.  It is very prevelant in any sitting position.  I almost feel like giving up its so frustrating.  I crossfit roughly 4-5 times a week.  Almost all of the pain is in the muscle between the SI Joint area and my side/hip.  Not sure if I am explaining this correctly but the pain travels along an area from the SI Joint along the top of the Gluteus Maximus then down into the side/hip area.  It does not go deep down into my leg and the pain is like a constant deep burn, never a very sharp debilitating pain.  I am open to any additional ideas and would love to know more about how to self evaluate posture such as David is refering too. So if I hijacked this post but it seems like many people are in similar situations and I’m just looking for any help I can find.

B