I'm firmly of the opinion that GI Stasis, or random gut issues, that pop up in rabbits is a latent form of coccidiosis. I've talked with vets and vet techs online about this and they pointed me in that direction.
Treat for that... your ENTIRE HERD, keep your cages VERY clean. DO NOT allow for wet spots in your cages where hair and bodily waste collect, not even one day. Treat any rabbits that come in and PLEASE... ISOLATE THEM for at least a month before letting them anywhere near your current herd.
Gut issues also tell a person about the immune system of a rabbit. Do not breed rabbits that get sick EVER. Doesn't matter if it's nestbox eye, poopy butt as a kit, a random sneezer, etc. Just don't breed them. It's all immune system stuff and you don't want to breed that into your lines. If you have a doe whose kits get sick or die randomly... stop breeding that doe. (unless of course, it's a management issue in which case fix the problem).