Can You Explain Why My Chinchillas Died?

I need some serious help regarding chinchillas. We started with one chin about 3 years ago and got another two years ago. They were both supposed to be males, but it turned out that our first was a female. They had one kit at the end of last summer. During the winter the female took ill and she started on antibiotics (at this point she was housed with the male and we thought she was pregnant). Their kit had already been weaned & was in a separate cage in a separate room. She started getting better & we had the male on antibiotics too as a precautionary measure. Ripley (the female) was nearly well and Kozmo (the male) who never showed symptoms suddenly became very ill. In a matter of hours he died in our arms. It was a very sad experience and a major loss. At this point we thought it was a bad strain of Bordetella that crossed species because we had just gotten a pig who came with kennel cough and all the dogs, cats, and myself (I have a weak immune system) got very ill, which happens very rarely and only with severe strains.

About 2 months ago Ripley gave birth to two healthy kits and we were overjoyed to know that she was able to handle the stress, get well, and have two healthy babies (a boy and a girl).

Our joy was soon met with disappointment when Gizmo (the chin in the other room) took ill. The next day after his symptoms began we took her to the vet and he informed me that he thought it was pasteurella, which came on suddenly because of the chinchilla's instinct to not become prey to predators in the wild. The vet treated Gizzy and we took her home, but two hours later she died. Again--it was absolute heartbreak.

Today we were met with sorrow again when we found Ripley dead at the bottom of the crate--her babies are fine. She had no symptoms of anything & appears to have died in her sleep.

What is going on? We buy quality natural chin food that is free from fillers & chemicals, we only feed treats in moderation, they have fresh water, a clean crate, daily dust baths, and are handled with the utmost care. Why have we lost 3 chinchillas in a five month span that weren't even in the same room. Oh and I forgot to mention that after the Bordetella outbreak we threw out the old crate and all of the supplies and started over in order to prevent cross-contamination or further illness.

Chins are supposed to live at least 10 years and ours have lived to be 2, 6 months, and 3, respectively. We love our chins and only give them the best of everything. Do you have any ideas what could be going on? Is there something we should be doing that we aren't? Should we be concerned about the babies getting sick? Should we get Ripley autopsied?

Please help; we are really getting discouraged and have no idea what to do!

Thank you!