Cathy Web,

I'm glad to hear that vaccinations were given. Unfortunately, until the whole series is completed, your pup may not be protected against parvovirus or distemper.   Parvovirus starts with a loss of appetite, then vomiting leading to diarrhea that smells awful and is frequently reddish in color. If your dog just started having symptoms (for example, just stopped eating and vomiting within the last 48 hours) a vet can prescribe Tamiflu which can help your dog survive without expensive vet care. However, you do need to positively know that he has Parvo. The only way to do this is to have a fecal test done. Read about Tamiflu here:
http://www.bi-mar.com/tamiflu.htm

Dogs with sensitive stomachs can have vomiting due to a change in food, but there are other reasons as well. Disease, worms, protozoan infections, liver issues and even not eating can cause vomiting. Eating a non food item can also cause vomiting. You can read about some of these below.
http://www.thepetcenter.com/exa/worms.html
http://www.peteducation.com/article.cfm?cls=2&cat=1622&articleid=727
http://www.petplace.com/dogs/giardia-in-dogs/page1.aspx
http://www.beaglesunlimited.com/beaglehealth_giardiasis.htm
http://www.malteseonly.com/shunt2.html

Pups of this size also can develop hypoglycemia which you can read about here:
http://www.petplace.com/dogs/hypoglycemia-in-dogs/page1.aspx\

So put a drop of pancake syrup on your pup's tongue to prevent low blood sugar and give him some energy. In the future feed your pup 4-5 times a day, taking the food bowl up after each meal so you know when and how much he is is eating since it can be important to know. This also gets him used to eating when the bowl is put down and not stuffing himself at one time and not eating later. He should check the dog food container and follow the recommended daily allowance for his size. Break that amount down into equal portions for the day and feed that amount. A little extra is ok, but do not put down too much extra.

The following site goes over poisonous plants. If he has ingested a poisonous plant you will need to have him taken into the vet immediately.
http://www.cybercanine.com/toxicplants.htm

Keep him warm (dogs temperature should be 101-102.5F). You can get some puppy formula or goats milk and feed the pup small amounts with an eye dropper every 15 minutes. Give small amount frequently to help prevent the gag reflex which would trigger the vomiting. If formula is not available, you can use water with a pinch of salt and sugar in it or use pedialyte to keep him hydrated until he can be seen by your vet.

The following symptoms should trigger an automatic trip to the vet: If your dog has acute vomiting and diarrhea lasting over 24 hours. If your dog becomes dehydrated. You can tell by pulling up the skin between your dog's shoulder blades and seeing if it flows back down normally. If it stays tented or is slow to return to normal, your dog is dehydrated and needs fluids immediately and should see a vet as soon as possible. If your dog's gums and tongue become pale and not their normal pink color. If your dog's rectal temperature is over 103F (101-102.5F is normal) If your dog becomes lethargic and non-responsive. If your dog has trouble breathing.   

I hope this information is helpful to you.