Have you tried giving her mushed up food? Maybe some really tasty and soft chicken and rice, or some canned food? If she's teething, her kibble might be to hard for. If she usually likes her kibble, you can add warm water to it and mush it, and maybe add some canned or something to entice her to eat. Give her ice cubes too, it'll ease the pain from the teething. You can give her ice made of water, or you can try freezing some chicken broth ice cubes if she is willing to try them. Since your distemper shot is in 3 days, I would go but tell the vet to exam her first before giving her the shot. Make the vet exam those lymph nodes, you can never be too safe. Let him know that you don't feel comfortable giving another vaccine so soon while she's feeling this bad. And if possible, delay the shot until she gets her appetite and strength back. Ask what are the side effects of the lyme vaccine, and try looking up some info for yourself. If they fit, then it might be a reaction. Put your foot down and be firm with the vet if they insist that nothing is wrong with the puppy. Sometimes they're not as thorough as they should be, or think some owners are just over-reacting. If your vet doesn't have the same concern as you, get a second opinion and see another vet. I'm sure a distemper vaccine can wait a couple more days, better safe than sorry. I hope your baby feels better 
