hi.
you may indeed have some muscle tightness and restriction but I'd start by looking at the hip in detail.
the position you describe is one of hip adduction, medial rotation and flexion. as you detail, these appear to be quite limited. this is a position that is used relatively often to stress the hip joint and a positive result (pain/limited movement) may indicate some sort of hip pathology. culd be as simple as early degenerative changes and capsular tightening. any decent physio could assess the hip in detail and see if its part of the cause of your problem. they'd more than likely assess your lumbar spine too and probably perform a thorough biomechanical exam.
what age are you? do you have a history of lots of weightbearing activity, eg playing soccer over a prolonged period? any other details about the problem?