For the past few months I have been suffering with random bouts of severe lower back and lower abdominal pain plus finding it very difficult and painful to stand up particularly after lying down from sleeping. However once up my mobility is reasonably normal although as I initially stand my knees will sometimes tremor. The pain remains the same in both back and stomach all the time. Then after about a week all will return to normal. Can you please explain why this could be happening. I am not over weight don t smoke and live quite a healthy lifestyle. Am 49 yrs old female. Nothing gynaecological as this been ruled out by go recently and by hospital tests.