Suggest Treatment For Pain In Ischial Tuberosity

I've had pain in the left ischial tuberosity for nearly a year. But the MRI scan and X-ray showed that there were no physiological problems with my hamstrings and hips. I am unable to do a developpe (where I have to unfold my leg), and I can't lift my lef high enough to put it on the barre during ballet lessons. I am also unable to stretch sideways or split.