..and if a dog is so ill .. then it may well just die anyhow
I have owned dogs for 50 yrs, worked at a Vets for many years ... and have seen more vomiting/diarrhoea than I want to remember ! There are many many causes - from very serious infections, to blockages, to other ilnesses in other organs , to parasites, to eating/drinking stuff ..and there is NO way anyone can tell , unless they are trained, and can see /touch the dog.
You are doing the right thing. Late, yes.. but the right thing .
I definatly will take him to vet frist thing tomorrow morning.