This maybe TMI, apologies if so.
Myself & LO have recently (last week) had a D&V bug (only gave him 24 hours with a bit of vomiting and dodgy nappy) whereas I was poorly for 4 days with intermittent projectile vomiting and diarrhoea. It cleared fairly well after that and thought we'd seen the back of it... Until today, when suddenly after 6 days of normal bodily functions, the loose explosive diarrhoea has started up again. 
I thought I'd been very thorough in changing toothbrushes, washing all bedding and towels on a hot wash, cleaning all surfaces thoroughly with antibacterial stuff, and yet here we are again.
Any ideas as to why this is? Or any ideas how to get my tummy feeling a bit happier? I'm considering kefir/probiotics?! 
(Feeling fed up at the prospect of another few days of feeling rough).