Vomiting in dogs can be due to many things including:
1. gastroenteritis (inflammation/ irritation/ infection of gastro-intestinal tract)
2. dietary indiscretion
3. foreign body obstruction
4. pancreatitis (infection of pancreas gland)
5. organ/ endocrine abnormality
6. cancer in older dogs
The blood is not too uncommon after vomiting multiple times, as the stomach and esophagus will be irritated ooze a bloody fluid.
We typically shoot x-rays to rule out an obstruction and run bloodwork to rule out pancreatitis and organ disease.
The majority of cases will be due to a non-specific gastroenteritis and conservative care at home can often relieve the signs.
This is what I would do for now:
1. Withhold food and water until he goes 6-8 hours without vomiting
2. Give over the counter Pepcid AC (Famotidine) at a dose of 0.25 mg per 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). If any diarrhea is noted, you can also give 1-2 teaspoons of canned pumpkin with the meals. The extra fiber helps firm up loose stool and promote normal colon motility.
4. This will usually resolve the signs in 2-3 days if a non-specific gastroenteritis.
If that does not help, then bloodwork and x-rays may be indicated to rule out other causes and getting an exam and work up would be ideal.
I hope this helps, let me know if you have any other questions.