Chompers, I've had unbelievable hip pain, too, at times. It isn't constant. My doctor told me it's bursitis and is very common with fibromites. He offered to give me cortisone shots in my hips but I declined because it comes and goes with me. But perhaps this could help you. You might ask your doctor about it.
I was sitting on the examining table and he presses, not really hard, on the sides of my thighs and I just about saw stars! I grabbed his arms and pulled his hands away because of the pain. The pain was in my leg and he said that this was bursitis. I guess the nerve runs from the hips down the legs so that's how I got that diagnosis.
I did keep moving. I used my cane when I had to and didn't leave the house to walk the dog without it. I couldn't go as far as usual but I did the best I could. So, I do encourage you to keep moving. Get up and down and walk a little. If you stay pretty much sedentary you will be even stiffer and have more pain. At least that's what happened to me.
Also, reread the gentle stretching exercises in Fibro 101. There are three that entail you moving your legs which would help stretch muscles around your hips, too. Check them out and see if this helps you too.
Sherrine