it could be something you ate....

But when this happened to my little one at 2 months old it turned out to be a gastro virus that she had picked up from her sister (2.5 years). DD1 suffered the vomiting and DD2 suffered a mild bout of smelly farts and watery/smelly poos. I ended up having to treat her with probiotics to sort things out so maybe keep that in mind too.

It's a bit of detective work really, anything change in his diet etc recently??