I get the suspicion that the Groin problem (one of my first symptoms before hell broke loose) could be related to a regional vasomotor dysfunction of a main artery, same as lower back. Feels like something is getting blocked (or change of tension) upon triggers like exercise, stress, heat, light pressure on affected area or body positions that put pressure on these (my mother who find it difficult to sit at a 90 degrees angle might have a similar issue, pinched tissue + weak vessels?), and POIS, like it doesn't respond properly, leads to weakness, fague minor pain and uncomfortable sensation. Plus veins on bicep did not respond well to blood pressure measurement lately with air cuff. Some pain in the body could be vascular related. I can also feel friction of blood flow in legs every now and then. The spasm in body, especially prevalent in legs, could be vasospasms.
Side note: I don't get these events anymore:
During POIS, pressure builds up in low part of spine, process could take tens of minutes. Moving around may delay this, unable to prevent this while asleep. Up to a threshold point that pressure is getting released and at the same time one leg shocks as if lightning shoots through it. Depolarization? Polarization builds up due to demyelination? (inflammation?). Or sympathetic outlfow issues in spine? Still have pressure in lower spine upon triggers but it doesn't keep building up, it doesn't reach the former mentioned threshold level.