You don't say how long this has been going on but, like ginger said, don't feed him!!
Yes, you can give Pepto but I would hesitate doing so if he is vomiting. I would definitely get him in to see a Vet.
No don't force feed him. Not a good idea. The reason he won't eat is because he feels sick, and his body cannot cope with food right now.
I can't tell you exactly what is wrong with him. This might be a simple stomach upset (in which case withholding all food for 24 hours, and just allowing water may cure it)....or there is something else wrong. There are a number of things this could be, from the very serious Parvo virus, to pancreatitis, to just having eaten something that disagreed with him.
The wisest thing to do is stop feeding him, and take him ASAP to a vet. If at all possible, take a sample of his poop with you.
Also -for future reference, be careful of baby food. Many times it contains onion powder which is not good for dogs! Small amounts of Pepto Bismol are OK....but here I do think you need the vet's advice -and soon.