You can go to petsmart or any other pet store and get a puppy milk replacer and some early start puppy food...they also sell vitamins at pet stores for dogs and cats. This would be ideal to get because the white gums can mean lack of nutrition, anemia, and lack of oxygen to vital organs. Fleas shouldn't be a huge problem in the colder weather, but if they do have a bunch, it's best to bathe them in a flea/tick bath to kill them off, because in little puppies and kittens an excess of fleas can cause anemia (the white gums). Keep them really warm, and if you feed them any fluids or food, make sure that you warm it up a little first. It would also be a good idea to take their temperature. Normal for dogs is around 102. If they are very cold, around 92 degrees or less, they are heading towards hypothermia. Keep them as warm as possible!
Also, if there is a lot of blood in their stool, it could be indicative of Parvo. The symptoms you are listing are all characteristic of the disease. In that case, you need to be extremely careful if you have dogs of your own. Parvo is an airborne disease and can be harbored in the surrounding area for up to one year. The ONLY thing that kills it is bleach. You need to clean everything you've touched and your boyfriend needs to be careful if he has any animals as well.
I'm kind of confused as to how you took them to a vet to get them checked out earlier, and now they are so sick. It would be best to get them emergency care right away. There should be an emergency vet somewhere in your area that you can at least call, if not take them to.
If you notice anything else, please let us know. I hope they are okay.