A friend of mine gave me a useful heuristic for the question 'should I try to work'.
Imagine you were going to do your favourite task - the kind of job that's the reason you went into the field. If you're too sick to do that, you're too sick to work.
I've also realised that I value my health less than I value achievement. I need to adjust that. If I value my health more, I will improve achievement. And happiness. And be able to spend more time with those I love, and doing things I love.
It was essential, when I started to get sick, that I learn not to fret about not having health. But the value system I created then is now hindering my recovery.