Hello, I am Dr. B, a licensed veterinarian and I would like to help. I do apologize that your question was not answered before. Different experts come online at various times; I just came online and wanted to touch base with you.
This is not good for Dougie. I have to warn you pups are high risk for dehydration and blood sugar crashes in these cases. Often we will see them sick like this with gut infections or when they've eating something they should not have.
Now if you think he ate something risky, he needs to see a local/ER vet ASAP to be safe. If not, then we can try home supportive care. First, to counter that nausea, you can try an OTC pet safe antacid [ie Omeprazole (0.25-0.5 mg per pound once daily), Esomeprazole (0.25-0.75 mg per pound once daily)]. Whichever you choose, give it at least 20 minutes before offering food to allow absorption. Though if he cannot keep this down, then that's a red flag that we need a local vet to bypass his mouth with injectable anti-vomiting medication.
While waiting for that to kick in, if this is making him weak (from low blood sugar), we can try boosting blood sugar by rubbing a sugary syrup (ie glucose syrup, honey, karo syrup, pancake syrup, or even non-grape jam) onto the gums. Once the stomach is more settled, we can try a light diet (eg cooked white rice with cottage cheese, scrambled eggs, boiled chicken, boiled white fish, or meat baby food (as long as its garlic/onion free)). These are easier to digest when the gut is not feeling 100%. As long as improvement is being seen, we'd give this until signs settle then wean back to a normal diet.
Since dehydration is a risk for vomiting pups, we need to check that. To do so, make sure his gums are moist (not dry), eyes are not sunken, and that he does not have a "skin tent" when you lift the skin. To see how to check these, here is a good video (How to Check Your Pet's Hydration- https://www.youtube.com/watch?v=KducLdeqGsM). If he is dehydrated, then he is best seeon at this point, to avoid this making things worse (of this makes them feel sick on top of being unwell).
Overall, his signs do raise concerns and we want to be proactive when they are this young. So, let's start supportive care but if he doesn't settle in a few hours, or if he cannot keep that or water down at any point, appears weak or dehydrated; then we'd want to get a local vet to assess as he may need fluids, injectable anti-vomiting medication +/- antibiotics to get him settled.
Finally, just to note in case you do need his vet now, I'd note some vets in our country have office hours today. As well, I wanted to mention that most practices have contingency plans for emergency care for their patients even when they are closed. Therefore, it is worth ringing the practice. If they are open, you can get in today. If they aren't, then they will likely have a message to direct you on contacting their out of hours service. And if you don't have a vet, you can find a local one via the RCVS Register (http://findavet.rcvs.org.uk/find-a-vet/) or Vets Now (http://www.vets-now.com/find-an-emergency-vet/) who are open all nights/weekends.