Chinchilla won't eat after dental

Hello my name is sophia. I have a chinchilla and his name is frizzles. 2 weeks ago frizzles had dental work done because his teeth were growing over his tongue. The vet said He had early signs of dental disease but it was best to file his teeth down. The reason why I brought him to the vet in the first place was because his paws started to go bald and his eye was running. I also noticed when he was eating he appeared to be gagging a little. He had the dental done and I'm currently giving him critical care 3 times a day because he lost weight. He's still not eating his pellets. He only eats about 3 pellets a day and today I noticed him gagging again when I gave him a treat. I have brought him back to the vet since the surgery and she looked at him and said he was fine and just told me to give him extra critical care.

Has anyone experienced their chinchilla struggling to eat after a dental? I'm just so worried about him. I don't want him to have to go through more surgery. He's 7 in June and has a heart murmur which makes surgery more of a risk so I'm all over the place with worry.