Yeah, an MRI is what finally convinced the doctors I had the problem (and they, of course, gave it the official names ... which mean I have a lesion from the vertebrae chewing into the spinal cord.)

I would talk with the Physical therapist after the results... the stretching is ongoing to help prevent the pain flares. If the muscles --especially the hamstrings- are not stretched regularly, and the back muscles strengthened (pelvic tilts and all that) that's a bit part of what causes the sacroiliac to infringe upon the sciatic nerve.

It's horrible pain. A vicious cycle.

Hope your MRI is soon, and the follow up quick. I wouldn't go for surgery without a few opinions (OF NON surgical doctors. You go to a surgeon for an opinion, he's going to think surgery!) Hopefully you really won't need surgery.