I And A 67 Year Old Female, And Had Physical

I and a 67 year old female, and had physical therapy for about 2 months at NewEngland Baptist Hospital-spine center for a Dx of piriformis syndrome (left leg) . An MRI revealed only an "aging spine", no stenosis. The PT helped enormously. I have been close to "religious" about doing the "take-home" exercises, and working with an experienced physical trainer at my fitness center on most of the same equipment used at the PT-spine center in the 6+ weeks that I stopped the PT. However it feels like my left leg/thigh is getting weaker, not stronger, and I cannot walk for more than about 15-20 minutes without pain right at the bone in my left buttock that progresses quickly to severe. In addition, the pain recurs at night when lying down in bed and is severely affecting sleep. Should I expect to have to live with this, or are there other treatment options I should pursue?