My chin had the same problem, she wouldn't eat, and she was very frail, lost a lot of weight, her fur started falling out and she had seizures. I freaked out and I didn't know what to do, until I was snuggling with her and was petting her, and I noticed that her mouth was very sore, I turned her over to her back and looked at her mouth, she had a chipped tooth! the reason it was giving her seizures was because she couldn't eat so her blood sugars sank super low, and then she wasn't eating because you can imagine just how much it hurt! next time if she has a problem like this, or if one of your other chins do, just check their mouth, they chip their teeth all the time from jumping around and chewing on stuff, the good thing is that it only lasts for a little while until their teeth grow.