How Can severe Knee Pain Be Treated?

I hurt my hamstring 3 years ago from over training. To the point where I couldn t walk. Negative MRI of lower back , knee, and hamstring. No divinities answer. PT did not help. Eventually pain subsided. Flash forward 3 years later, I can sprint and run and every now and then I get sharp pains behind my knee on the inside. Sometimes it s just in that area, other times it s high up under my butt. Some days I feel amazing, other days are painful to walk. I am athletic. Work out at least 5 days a week, and have a job where I need to be active. I don t know what to do anymore.