Any ideas on what is wrong with my dog?

First and foremost, I am taking him to the vet tomorrow as there are no er vets less than 300 miles from where I live. So please don't tell me the obvious of take him to the vet. I have a 2 year old heeler/aussie mix. I just returned from vaca and my neighbor didn't call me and tell me anything was wrong. for two days, he has had diarrhea and vomiting (no blood). Until an hour ago he was drinking, eating, playing, etc like normal (excluding the diarrhea and vomiting). Well, he isn't eating or drinking now. Does still energy, but isn't the usual following me all over energy. I did take him to the park earlier and he was normal there too. does anyone have any suggestions other than take him to the vet?