Oh, dear 3 days is a long time. If you look at his gums, do they look pink, or are they pale in appearance?
Has Tank had his puppy vaccinations against distemper and parvo viruses?
If he has not eaten in 3 days, won't keep water down, and is vomiting, he may be dehydrated by now. This could be parvo virus, or some other virus, or that he ate something that either disagreed with him, was spoiled or toxic, or is causing a blockage in his intestines. It sounds like he needs medical attention, rehydration, injections of nausea medication for the drooling and vomiting.
There is not much you can do for him at home if he won't take anything by mouth. If you could get anything into him, the most important thing is fluids: water, broth, or Pedialyte. You can give him Pepcid AC (Famotidine) for the drooling and vomiting: 5 mg per 10 to 20 pounds body weight, twice daily. If you can't get anything into him, he needs to see a veterinarian today. If his gums look pale, he needs to see a veterinarian as soon as possible.