Seriously maybe you should give up rabbits as you seem to have a problem in keeping them in good health. Dogs and cats may be a better fit as they don't die so easily and pretty much any vet can deal with their health problems.
I don't think we should discourage a person, on Rabbit Talk of all places, from owning rabbits. Yes, Cosima has had lots of health issues with their rabbits, but that shouldn't necessarily mean no rabbits at all. Instead, we should give up on practices we have that cause negative impacts on our rabbits and their health.
@Cosima, I am so sorry that you keep having problems with your buns. I know it must be difficult for you both dealing with this and having limited information for therapeutic plants to alleviate your rabbits' ailments on your side of the world in Indonesia.
I recognize this has been stated in the past to you as well, but I think you should be reevaluating your setup and feeding practices. From what very little I have read from
this book, it seems a major issue for meat rabbits in Indonesia is parasites and cleanliness of living areas. It is also possible you have inadvertently offered, or the rabbits have found for themselves, something that is toxic to them causing the bloating you've seen.
What I would suggest is thoroughly cleaning their enclosures. If you have access to disinfectants like a bleach; use that. Be mindful of the bleach runoff, though, as it will kill plant life. You'll need to make sure it is diluted enough to not cause harm when you are discarding it. Ensure there are areas that cannot collect urine or feces build-up and can maintain a level of hygiene for the rabbits. The book I linked above mentioned that switching from deep litter (which I don't believe you are doing) to bamboo slats or wire mesh bottom cages improved the health of the rabbits. It also suggests cleaning their enclosure floor daily. I know you were at one point wanting to do a colony, but cages may be the safest bet. Keep them up off the ground, away from their waste and any possible parasites or diseases in the soil. Clean their enclosure vigorously and frequently.
If you have introduced any new foods into their diets that aren't known are 100% rabbit-safe, stop feeding that. Give them only what you know is 100% safe and healthy for them. If you were ever unsure, either don't feed it or give it to a fryer that you were planning on dispatching eventually anyway.
Another thing to consider is their water source. Is the water clean? Do you offer them the same quality of water you drink? Is potable water difficult to obtain on your island? Perhaps boiling any fresh water on the island first prior to offering the rabbits would be smart. It may become quite a chore, but at least it could help narrow it down should you see any improvements after giving them cooled water treated by boiling.
Keep us updated with how Ghost and your other bunnies are doing. Please also let us know what steps you have taken to help prevent more health problems with your rabbits as we can better tailor our advice.