The five placentas could definitely be the reason for the stomach upset, but I would take her temperature just in case there is something else going on. If it is 103 or over I would seek vet attention immediately.
Tube feeding is probably your best option at this point. Call some ads in the paper for toy breeds and see if anyone can help you. Also bird breeders have the necessary equipment. It is much easier to tube feed a bird though because everything is so visible. If he is staying close to Mom and not wandering off that is a really good sign.
Here's a link that gives a good handfeeding formula. You must feed the formula at 101 degrees, 1 ml (slightly less than 1/4 teaspoon/ 5 ml equals 1 teaspoon) per ounce of body weight every 3 hours around the clock. Never feed a chilled pup, warm first. Feed with an eye dropper since the sucking reflex is too weak. If you cant get the puppy to take it all you will have to feed less more often, every hour, every 30 minutes whatever it takes, even through the night. Always feed with the pup lying on its stomach.
When you feed, does any formula come out the nose? If so, you may have a puppy with a cleft palate, but there have been a couple of YTers who have done well with them so don't let the vet put him down right away.
http://www.leerburg.com/bottlefeeding.htm