Thank you Thompson for your kindness. I expect she has tried various positions/ways to improve her breathing (she's a retired consultant anaesthetist, so knows about O2 levels and so on). Her latest e mail yesterday said she has used a pulse-oxymeter thingy, and her levels are quite low. Also, her lungs are filling up again, but she's managing to clear them each morning by heavy coughing.
She's naturally quite depressed at the thought that she might never regain the robust health she enjoyed recently before this virus (she's a lot younger than me).
Please everyone, keep vigilant and try to prevent ever catching the blooming plague!