I am so sorry to hear this. It is very hard to distinguish whether it is progression of HSP or something else. My DH went from being still just about able to manage the stairs to not being able to after having Covid.
Now you have your own health worries on top, it is just not bloody fair, is it? 💐
(BTW, I have had a name change in case you are confused. I am the poster with the DH who has HSP).