Nige
Nige There must be something in the story which is trotted out. Marathon runner can push through pain, barely impacted but come the end of the race after resting, can barely walk. Why can the brain ignore pain (that it has created/interpreted) but then not ignore it. Why does running or a distraction actually trump pain - one of the most obvious things the body would need to react to ?
That’s the adrenaline that builds up in your body, help push you through that you are in the moment, so to speak. Once the “emergency” is over, you are out of the fight or flight situation. Your body crashes. Don’t know if you remember the mountaineer Aron Ralston who had to cut off his own arm when he got it trapped in a canyon in 2003. It was the buildup of adrenaline in his system that got him through that. Same goes for women going through natural child birth. Your body gets you drugged up to such a high that, even though you are aware the pain is there, you are on enough of a high to not care. Bit like drug addicts and wino’s, only there’s are not the natural highs of adrenaline. The adrenaline junkies are the ones who’ll go for the more extreme sports and don’t fear pain.
Adrenaline comes from the adrenal gland situated at the top of your kidney. Might be a direction for you to explore. Also, consider looking into how those with spinal injuries manage chronic pain.
https://www.spinal.co.uk/
https://www.healthdirect.gov.au/adrenal-glands
Another avenue to be considered/explored, if not already, is hypothyroidism as it can cause chronic pain too
‘hypothyroidism may cause: Muscle aches, tenderness and stiffness. Joint pain and stiffness, particularly in the hands and knees in adults.’

https://pubmed.ncbi.nlm.nih.gov/32621001/
How deeply/thoroughly was your chronic pain investigated? It’s easy, and less expensive on NHS, just to conclude its the result of your stroke and you’re just going to have to live with it. But have they even tried to track it down, the pain has to stem from somewhere in the body doesn’t? Is it because the brain signalling to the thyroid or adrenal gland or elsewhere causing something to malfunction.
For instance, I have a little “thin” pain just down a section of my outer thigh, a couple inches long, it came on immediately after my stroke and it’s relatively constant. I can live with it and comfortably ignore it but I know its there. I think I mentioned it to physio at the time but never bothered with the doctor as there were more pressing issues at the time, my speech for one.
I just assumed it was the stroke effect! But now, 4yrs on, with my physical fitness regime, the pain is not as great as compared to the beginning. I can not pin point exactly where it stems from and it’s coming from the hip. I can actually switch on and off just by turning my leg certain ways. That in turn, tells me its osteoarthritis; I’ve had it in the left hip and had that replaced but the right hip, my stroke side, isn’t bad enough for that yet. Like I said, its easy to assume otherwise, and cheaper on the NHS.
I can only wish that yours could be that easy, but you are far worse off than I ever was ☹