Chinchilla has pneumonia, HELP!

So Falcor was taken to the vet a week ago because of sneezing, they gave an antibiotic for what they thought was a URI. I found him in his cage yesterday after hearing a weird noise and saw a saliva bubble hanging from his mouth and rushed him to the vet right away. They did X-Rays and I am waiting to get a call from the radiologist about them, but the vet said it's either pneumonia or heart disease. She gave him a stronger antibiotic, and a probiotic. He's been eating lots of hay, and was at his food bowl this morning, but I'm thinking I'll try to feed him some critical care also to help if there's any digestive problems because of the medication.

I just wanted to know if anyone has had any experience with this and any tips on helping him get healthy again, especially from those who have gone through this or are experienced breeders. I really don't want to lose my furrbaby, he is my world.

Thank you so much,

<3 Kayla