Heart breaking here! Please help!

About 2 years ago we started with a few buns. Now we have many. Last summer we had a sudden and awful bout of bloat hit our rabbits and we lost a lot. Mostly does with kits and also kits. We were able to save some. The only thing we could pin it to was the kibble we were feeding (not enough vitamin A). So we changed to Blue Seal Show Hutch and everyone has thrived since then. Fast forward to this Spring… we have had SO many kit losses. My heart is absolutely breaking. They do AMAZING until it’s time to wean. From within a few days if weaning to a few weeks, they start passing. They will be completely fine! Eating, drinking, peeing, pooping, playing, etc.
They start with lethargy, not eating/drinking, some bloat (nothing crazy and sometimes none at all), then complete weakness and can’t even hold up their head. Then they pass. It happens within 24-48 hours.
We have changed from Orchard hay locally bought to Timothy hay from Tractor Supply. We have tried adding and taking away extra Alfalfa. We have changed bedding from straw to hay, now pine shavings (the big ones). We have treated with penicillin which seemed to help my adults but not kits. We have also dewormed using Pyrantel and now (months later) fenbendazole.
I am at a complete loss at this point.
No small/exotic vets are anywhere near me. We are VERY rural. We need some help here. Please!

[Am moving this to where our breeders can chime in.] Could you provide some background on their housing situation and/or post some photos of that? Are they outdoors? In hutches? At what ages are they being weaned?

They are inside in cages. They are being weaned at 8-9 weeks old.

This type of cages.

A common issue that can affect weaning age rabbits but doesnt as much affect adult rabbits is coccidiosis. Upon necropsy, a rabbit with coccidiosis will have pale spots on its liver. They do make some medicine for it such as corid that you can purchase at a feed store, but you would probably have to try and find the right dosage somewhere else - the corid sold is mostly for calves and other more common livestock. Blue seal is a good brand of feed. I know a lot of people that do pretty well on it. Of course, it varies mill by mill and every company might have a couple bad batches but I would probably look at other issues than food at first.