"Basically bedridden, sick with 'flu', only it's not flu." sounds symptomatic, whatever it is, and we don't yet know it's not what this thread is all about.
If I hadn't been generally concerned about mother, I probably would have wished for Greiger to get well soon as well. As indeed I do, let me now say.
But as a definitely symptomatic-of-something contact (groceries-picker-uperer, at a minimum), the only 'good' news is that risk-group mom isn't showing any not-flu symptoms[1]. Not good enough for a health-critical decision, but room for optimism in this otherwise disinterested observer.
BTW, right now I've got a tricky problem to work out. Scottish policy is basically no visitors ("social visits") in private homes, but England allows bubbling of two households (of limited numbers). And I'm trying to work out how that applies to an extended car journey that I may be taking, with someone not of my household, in two weeks' time - planned before the relockdown - that actually crosses the English/Scottish border. If it was public transport, it'd be allowed (masked and in wider separated seating) and we were going to be doing it as a bubblish thing (going by stricter rules than then required to follow). OTOH, we're "outdoors", technically (too early to tell if we can keep the windows open) and not facing each other so could perhaps have worked with the 1+m distancing. We should be safer (combined) than any other form of travel other than actual cycling from place to place, but "the rules" look like they need a bit of flexing to squeeze into.
Could just declare ourselves a 'travelling' household, for the duration. (Not too much of a problem to requarantine ourselves seperately at journey's end, even if one home nation puts the other home nation on its "dangerous point-of-origin" list. So long as they don't re-erect Hadrian's or Antonine walls to prevent all movement.). But two weeks is a long time, potentially, and plans may well change without my needing to actively worry about these things.
[1] Over-a-week since presumed infection, two days since became ill. Therefore five+ days to get laid low by the whateverness. If it's jumped again, it could have done two, three, four days ago, assuming constant/daily contact, so I'd stick my neck to say it either hasn't happened or it did and actually got nowhere for whatever reason. But far too many guesses in there, so don't take this as a medical opinion (IANADoctor!), this was just how I first worked it out in my head.