What Causes Pain In The Hips?

I have mild hip pain in my left hip. I say mild, because sometimes I don t feel it at all, but most of the time it feels like a pinched nerve & I walk with a limp until I walk enough and the pain dissipates. Im a school teacher who walks from one classroom to another all day, so I do move around quite a bit. I had it x-rayed along with my right knee ( showed arthritis) , but the knee no longer causes me pain, & the bone specialist didn t see arthritis in my hip. I do 4-5 ; 20 minute workouts a week. The personal trainer calls it LeanFit because it s not as much strength building as CrossFit workouts, but similar Workouts (less weight, more cardio). I ve always been active, but this hip pain seems to be getting worse, rather than better. Do you have any suggestions on how to get rid of this hip pain?