I had Sciatica in my right leg and was in severe pain for about 8 months. As it, at last, began to get better, I started getting pain in my left thigh and knee. When the right leg finally got better, I went to the doctor because of the severe pain now in my left leg. After x-ray, it turned out I had very bad arthritis in my left hip (my pain was referred ). My doc said, the body only registers severe pain from one source at a time. She then cheerfully said, when I have had my hip replacement done ( soon I hope), I will probably start feeling pain in my right hip, which has arthritis too. This may be your problem.
I sympathise with the waking up at night. I do as well and have to get up for a while. Only about 3 times a night though, so not nearly as bad as you.