Pain in the hip/butt/leg can be a number of things, but one of the most common causes is the sciatic nerve being pinched. A strong lower back and abdominal muscles can help.
As always, get Doc's advice before working on them.
One of groups of excercises that I do for that area is a Nautilus lumbar machine workout for the lower back, alternating with Nautilus crunch machine for the stomach muscles.
You can also do "good mornings" and "butterflys"
for the low back, and crunches for the stomach without any weights or health club. Your doctor should have a leaflet describing those excercises.

I have also stepped up the neck machine excercises to build up where the ENT gutted me.
I work all four sides of my neck, and do shrugs
(holding a bar at waist level and pull up, trying to make my shoulders touch my ears.)
I have no more tingling from my neck, and I'm getting alot of feeling and facial movement back.
O-O