My wife uses a tapered seat cushion.
My advice: I started having some back pain along with leg pain in my right leg. Then my hip. Had trouble sleeping, driving, sitting. Thinking I was due for a hip replacement I went to a well known hip Dr. After exam, xrays, and MRI the consistent conclusion from all was no, hip was fine. BUT problem was spinal stynosis (sp?) in my lower back. He did not recomend surgery but insisted on physical therapy. I went to the same physical therapist I had for my rotator cuff therapy. She looked at the data, showed me where the problem was, explained what caused it, and what therapy could do. her first excerise I started on started the road to recovery. Did therapy twice/wk for a few months and the pain is basically gone. I get occasional "twinges" but as long as I do some excercises each week and pay attention to what the therapist said, I'm back to normal.
So, my advice get a checkup from a orthopedist and see what they have to say.