Rehab for mild hamstring pull?

It might not be able to be resolved because P.T. didn't do any good--in fact thee PT evaluation in and of itself made my left leg numb. I think there is some kind of permanent structural and/or nerve damage in this area and any kind of twisting will make it worse. I have done exercises for 2 years and have not noticed any improvement. I'm just lucky it isn't as bad as it was 5 years ago! I think the PT person was somewhat scared when she did my eval and noticed that just resisting pressure side-to-side as she held my leg then caused the numbness to return. I had NO pain during the evaluation and no indication anything was wrong but the next day the numbness was there. It lasted for a year, which is what happened when I first injured myself by sitting twisted in a chair for 3 hours while they were doing construction in the office. Ow...
I'm open for any ideas and suggestion though, but so far the Dr. and the PT person I have seen are puzzled.

Have you had an MRI done of your L5 area?