It is the hips out of line which really irritates this muscle.
I often sit with one knee up, and the other folded under me, or with both legs folded with feet to the left. (do you know what I mean?) Is that going to aggravate this problem? It's the side with the knee up (left side) that is painful. What would you recommend for sitting? Is cross-legged OK? Can the chiropractor help me with this?