A good stretching program may help you. You want to stretch your legs in all directions, front, back, sides, not just in one direction and not just the stiff one. You should be able to find some routines on-line. Hold the stretch, don’t bounce, for 30 seconds, relax, the stretch, pain free, for 45 seconds, relax, then hold the stretch for one minute. You have to teach the muscles how to relax. It can take time, but it should help in the end. Strengthening in all 4 directions should be done too.