Hello, I'm Dr. Deb and will do my best to help you today.
I'm sorry that your dog isn't feeling well although that's good that his gums are a normal color and that he's not lethargic.
It's possible that he's picked up a viral or bacterial infection (we can bring these pathogens into our homes on our shoes) or he may have developed esophagitis from all the vomiting that he's doing.
My suggestions would be as follows which, hopefully, will be enough to get him past this:
1. I'd give him over the counter Pepcid AC (Famotidine) which should help with an irritated esophagus and possibly help to control his nausea. The dose would be 1/4th mg per pound of body weight twice a day.
2. I'd withhold food for at least 8-12 hours and just give everything a chance to settle down.
3. I'd probably not offer any water either for several hours. Then see if he wants to drink but only offer a small amount. If he doesn't want any, then you can dribble it into the side of his mouth with a syringe or small turkey baster.
Another option would be Pedialyte which has electrolytes to replace those lost.
4. If his nausea appears controlled, then offer a small amount of boiled, skinless, boneless chicken breast and 20-minute white rice but only a small amount at one time.
If he continues to vomit, however, then a vet visit may be prudent.
I hope this helps. Deb