Chronic tension right leg

32 years old 72kg in weight. I raced road cycling for 3-4 years at a high amateur level. In the end I had to stop because of this injury. After exercising I feel an extreme tightness when I try to extend my right leg into a fully stretched out position. The tension feels like it is in the area between the hamstring and the vastus medialis.

I have seen many specialists, had lots of scans but never found the root cause of the problem. However one time a physio did a very deep tissue massage around the top of the calf muscle and popliteus muscle. I left the clinic that day with all of my usual symptoms gone. Very poor flexibility on toe touch on right side, right foot always wanted to rotate outward. For a couple of weeks I felt 100% normal again, until one day I did a longer than usual cycle. After that I was back to square one. Further manipulation of this point never gave me the same relief. Any tips on what could be going on? If you need more specific info please ask. Eoin