I Would Like To Know Potential Causes Of Persistent Muscle

I would like to know potential causes of persistent muscle pain (it feels like strained muscles) in my thighs, accompanied by a feeling of joint and muscle irritation around the sockets where my femurs mate with my hips. The pain levels vary somewhat, but have been present for at least 2 months. It seems to worsen with prolonged inactivity (lying in bed) and sometimes improves with activity-sometimes not. I have been experiencing some sciatic nerve pain, primarily in my right buttock and in the back of my right thigh. It is sometimes difficult to separate the 2 problems, but that doesn't seem to explain the same persistent muscle pain in my left leg. There is also a feeling of strain in my left shoulder which is not responding to rest or lack of use as I would expect.