12 months would seem a long time for a purely muscular problem, unless some other biomechanical/neural factor was involved. A "Neural" problem could be many factors acting on the nerve: Compression, Tension or Irritation. It's common to feel the affects of this elsewhere, e.g. Hamstring, Calf or Tingling toes etc, and not necessarily at the site of the problem. Each will have it's own method of treatment too.
I can't offer any medical advice just some experience. I don't wish to frighten you but as an extreme example my partner had suffered for quite some time with increasing pain/sensations in the lower back, buttock and hamstring on one side. This eventually after two Mountain Marathons and whilst training for a third led to her taking quite some time off work before an MRI scan eventually revealed a colossal disc herniation compressing two thirds of her spinal chord. A week later she was under the knife getting the disc material removed.
I mention this because it took months of seeing doctors/physios before they were sold on the idea that an MRI was necessary. Especially as she was still very active both running and horse riding.
Not all doctors/physios will be as experienced as others when it comes to neural examinations either so getting a second opinion may help or referral to a specialist. You may have to wait a while though.
Best of luck
Jim