I suppose it was the lemsip that did it then. Would an empty stomach have an effect too? It's very sad and bloody unlucky.
apple toilet training depends on when they're ready. There's no set age. DD1 was trained at 2.1 - the first couple of days were not brilliant, after a week she was clean then had a day long relapse at about 10 days. Since then she has had one accident, maybe two. She still wears a nappy overnight but it is always dry in the morning - she refuses to go to bed without one though 
I chose to train her then as it was spring and warm enough to run round nappy free and she had started developing thrush and nappy rash, so no more nappies cleared that up very quickly. It was easy after the first few days, except for the regression day. I toilet trained a toddler as an au pair - she was 18 months (the parents insisted) and that was much much harder.
From what I've heard boys are ready later than girls. I think I'll possibly try with LO during her summer break from nursery in August, but will give up very quickly if it is too soon, then will try again when she is two, or maybe leave it til the Christmas holidays when she'll be 2.2 and will have two weeks off nursery. But won't try in summer if she doesn't seem ready iyswim. There's no point - if they're not ready they turn it into a battle that you can't win (my neighbour is going through this atm as her French paed has been piling the pressure on
- my Lux paed is much more relaxed about that, and speech, and milestones in general than the French seem to be) But you'll know when he seems ready.