Not a doc but it sounds just like
Sciatica - Wikipedia, the free encyclopedia, originating from lower spine.
Long sitting in the wrong position or chair probably stresses it, and/or weak stomach muscles or digestive problems could help pull things out of whack.
I'm guessing, but it also be hip joint or tissue scarring/circulation/other of the muscle groups around it if not that.
Long sitting is known for heart problems, eventually. The blood/lymph pools in the legs without circulating and getting filtered, then clots, breaks off, and ends up in the heart or brain.
Try walking around every 15 minutes or so, sleeping with your legs elevated/back flat, and do mini-crunches and mini-leglifts to strengthen that area. The lady will also thank 'ya
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