I also have had the same type of pain. It's been extremely hard to sleep at night. My gp referred me to an orthopaedic dr, who took xrays, showing nothing, and then sent me for an MRI. Is it possible you have a pinched nerve in your neck area? I'm now being referred to a neurologist, because the MRI showed multiple disc bulges and bone spurs, which they think are affecting nerve roots. It's just a thought... I think I've read that muscle atrophy can be caused by nerve problems too.
I don't know that this would have anything to do with your hip problems though.
Good Luck!
My mom has had this in the past. Her arm was hurting for about 5 months, and she went to two clinics. They told her to just rest, that she probably pulled something. It is gone now. But when she had it it only hurt at night. Strange.