Welcome to JustAnswer...my name isXXXXX a licensed veterinarian, and will do my absolute best to assist you.
How old is he? Is he current on his vaccinations? What breed? Particularly parvovirus. The black and tan breeds are more susceptible to parvovirus.
He is about 4 years old. A chihuahua/terrier mix. He is current on his vaccinations
I'm 99% sure he's had his parvovirus within the last year
This could be many things; but first, I want to let you know that it could be an emergency if the bouts are occurring every 20 minutes. Could be he ingested a foreign body, pancreatitis if painful in his abdomen, a severe gastroenteritis, still could be parvovirus. He should be seen at an emergency clinic before he becomes dehydrated and anemic. Since he is a small dog, he will dehydrate quickly with the diarrhea and vomiting.
He goes straight for his water bowl as soon as he throws up or poops
I should take him in now then?
Does he keep the water down or is he still vomiting? Is there blood in the vomitus?
no blood in the vomitus. mainly clear.
he keeps it down for about 20 minutes and then vomits again
You should get him to an emergency clinic now as this is a major problem.
okay. I will take him in right away.
Good luck with him. You are very welcome.