Thanks all for the lovely messages. Sorry I'm so late in acknowledging them, I've been really quite ill myself (on the mend now, phew).
Lazydaisy, it is Meniere's disease. I'm so glad to hear your vertigo was helped. She says she's been told by a doctor that exercises would be dangerous, but I'd like to check that next time we go to her GP, because if it is possible to overcome this problem, it'd be a big help.
Robert, thank you. My main bugbear with her acting "well" is that she even convinces herself that she's capable of doing things she shouldn't, or just doesn't care that she might hurt herself, so she doesn't think to ask anyone who might be available for help - meaning it's always down to me to step in. If she didn't have a track record of damaging herself at times like this, it wouldn't be anywhere near as much of a worry. You're quite right we just feel the need to have a moan sometimes - now I no longer feel at death's door I look forward to joining the forums, and not just to moan!