I have arthritis in my left knee, and damaged the ligament in my right from a winter cycling fall, but when I did the CF they both felt super, especially as I had just done 500km of cycling in France beforehand. Going over to Roncesvalles from SJPdP didn't feel at the time like a problem, but by the time I had done the descent into Zubiri, my knees, especially my right one had began to hurt. At this time I wasn't using a walking pole. By the time I reached Pamplona my knees hadn't gotten much worse, but just in case I called into the Decathlon there and bought an elasticated knee support, having foolishly not taken one, and started wearing it on my right knee. Well this just made things worse, and by the time I reached Villamayor de Montjardin my knee was hurting so much that I couldn't even lie down with a straight leg, and had to sleep sitting up, propped up against the bedhead (not easy when you're on the top bunk)! The next morning I struggled setting off, having written in my notes that I was having thoughts on whether I could continue, and by the time I got down the slope at the bottom of the village, I had to stop and sit down. But some determination not to give up put in my mind to try it without the knee support, so I took it off and gingerly continued. And as I walked my knee began to feel better, and I was able to carry on after all, later finding a disgarded walking pole in an albergue donativo box which was helpful all the way to Lavicolla, and where I left it in another donativo box.
In retrospect I realized that the knee support had been restricting the blood supply to my knee, even though it hadn't felt too tight. But if I hadn't been struggled with my knee in Villamayor, I would have walked further and not have met several wonderful people, two of whom I ended up walking the rest of the CF, and still remain in contact with!
You may we wondering what this tale of woe has to do with the OP's post? In my mind it is that we shouldn't be deterred by what might seem like overwhelming health problems, and if we really want to do something we should just go for it! Facing adversity often also leads to unexpected and positive outcomes.