Thank you, peeps. The news is good. Mum was kept in hospital for two nights while they did tests and interpreted results. The discharge on Friday said that the likely reason for her collapse on Wednesday was "postural hypotension", which I think means she fainted. This was always a possibility in my mind but with the paracetamol issue and her age and thinness (I feared broken bones initially) it was important to get help and checks.
My brother took over from me on Thursday after his return from holiday. I took him to see mum in hospital that afternoon as he wasn't fit to drive (jetlag) and, while I was there mum told him she'd only been admitted to hospital because there was "no-one else at home". This hurt at first but now I rather hope she forgets all about my two-week presence because if she remembers about my removing paracetamol from her bag I suspect I will never be forgiven. No regrets. I did what seemed right at the time.
I'm now back home and, basically, shattered. Thank you all for your support.