Hip pain only walking uphill

Hi, advice please on diagnosis. 59 yo pt has L) sided hip pain but only walking uphill. Pain decreases on flat & when running. Has had previous history of L5/S1 nerve block injection. Gets some low grade back pain, but this is manageable with exercise. L) hip flexion ROM slightly reduced EOR compared to R) but hip feels normal. Bilateral tightness in calves, hams, quads, QL etc - admits he does no stretching. Hip special tests all -ve. Glute muscle firing pattern good. Anything else I should be looking at? Thanks for your time :)