I"m not sure what you mean….

by SIDP…Do you mean sub-acute CIDP? IF so, the acute, sub-acute or chronic onset I always thought applied to how long it took to come on and then ‘hang on’.

It sure sounds, and I’m no doc by far, that you have some sort of chronic version…relapsing or not. More importantly is what the doctors are doing by way of treating you to keep any flare-ups from happening and knocking you down flat. Ultimately, only you can determine what you REALLY have, whether your doc[s] agree or not. Only you can crusade for whatever treatments or therapies you might benefit best from.

As far as symptoms disappearing? Do you mean you get totally back to normal? Or, is there some damage? You could be healing in some ways and then be ultimately ‘deteriorating’ in other ways in other nerves or areas.
This all is why no neuro will ever say definitively that you have X or Y! Nor will they say that you will recover! They always are optimistic but hedge the bets all over the table. That’s because each of us is different, we respond to treatments differently as well as come down with this stuff differently as well.

The only key to sanity for me in all this is trying to keep a good attitude. Yes, it is practical to file in the back of your mind what is the worst that could happen, but don’t let it interfere with your determination to achieve any and all bit’s of normal that you can find!