It's hard to tell whether this is true vomiting or regurgitation or even coughing/ gagging and lung signs. If it's more vomiting then I'd think gastroenteritis or even a foreign body obstruction or pancreatitis
. If coughing, then I would start thinking about kennel cough
or even pneumonia.
This is what I would do for now:
1. With hold food and water until he goes 6-8 hours without vomiting
2. Give over the counter Pepcid at 0.25 mg/lb every 12-24 hours
3. After the fasting period you can try either a bland diet
of broiled chicken
/ hamburger and rice. If not available, you can just give small frequent meals (3-4 meals/day rather than 1-2 meals/day).
4. This will usually resolve the signs in 2-3 days.
If that does not help, then bloodwork and x-rays may be indicated to rule out other causes.
I hope this helps, let me know if you have any other questions.