My puppy was bitten by mom, injured, in pain, not eating. What to do?

The pain is an issue but the most important issue at the moment is the infection he has developed, you must take him to the vet ASAP, he will need a course of antibiotics and pain killers (you can't use human pain killers for dogs).

Unfortunately there are no OTC medications you can give this puppy, especially not pain relievers. Many are toxic to puppies and can be fatal if given. Keeping her separated for now is a good idea, and you will have to feed her with a puppy formula while she is separated. A brand I recommend is called KMR, and you can get it at a grocery store. Bottle feed her tonight, keep her warm, and definitely take her into the vet in the morning.

You must take him to the vet urgently, dog bites always get infected and that is probably why he is showing those symptoms. it is also very painful and he will probably need pain killers as well as an antibiotic course in order to fight the infection.

Dollar is suffering from a severe infection due to the attack and is also most probably very very painful. you must take him to the vet urgently he will need a course of antibiotics and pain killers.

This sounds like a bad situation. Yes euthanasia may be the most human option, however, if that is not an option for you than it is VERY important to involve a veterinarian so that the puppy can be protected with antibiotics and something to help with pain. Your veterinarian may advise a surgery to remove any bony remnants if the traumatic amputation left behind parts that could lead to pain and arthritis. Please, please take her in for some antibiotics at the very least. She could develop a life threatening infection.

He needs to be taking antibiotics every day for 1-2 weeks, he also need to take pain killers as he is likely to be in pain, you need to continue the treatment in order to see if he is getting better or not.

You pup was obviously injured by the older dog, you need to take him to the vet urgently in order to get him checked and treated, you will need to completely separate the two and you should seriously consider having your older dog neutered as well.