Honestly I’m not on the spectrum at all (that I know of) and your SO’s half of those exchanges sounds utterly exhausting.
Like, in their shoes, I’d probably just start sharing less and less about how I feel, especially when I’m not feeling well, specifically because I wouldn’t want to have to play 20 questions every time until you finally gave up on the analysis.
Like, I totally get that you’re just trying to help because you love them…but maybe you could simplify the process (and cut to the chase and give them some more agency) simply by saying something like “Ugh, I’m sorry you’re not feeling well. Is there anything I can do for you?”
That lets them express their own thoughts/feelings/desires without having to pass a gauntlet of questions.
Again, I totally get that you mean well (I end up on your side of this exchange whenever my own SO isn’t feeling well…you just want to fix it for them), but I’ve also learned by time and experience that often my best move is to offer help, and if the answer is just needing some time and quiet, I just tell my SO what I’ll be doing nearby (but not up in their business) and if they need anything at all, just let me know and I’m happy to help.