you have to keep them inside as they are sick. They can't fight the cold and fight the sickness at the same time.
Your vet is not a rabbit savvy specialist, you should see a rabbit savvy specialist instead.
You need to check if there is bloat on the stomach, is there stomach hard or soft? If it's hard, that's very dangerous, they might only have 12 hr. left. You need to get them to rabbit savvy vet, and the vet will know how to get a tube inside the mouth of the bun, and suck the gas and stuff out.
If their stomach is soft, read this link:
http://forums.rabbitrehome.org.uk/showthread.php?t=124510
critical care is good, but it smells bad, I don't use it anymore. As rabbits don't like the taste or smell.
DO NOT FEED YOUR RABBIT WITH ANYTHING (FOOD NOR WATER) IF THEIR STOMACH IS SUFFERING FROM BLOAT
I came up w/ this idea that I have use to 1 of my bridge bun for over 1 yr:
1) Get some non-meat baby food, use a syringe to suck up the baby food, get a cup of hot water, dump the syringe in the hot water for 2 min., now the syringe is warm, so you now syringe feed the baby food to your bun.
Every 1Kg of bunny weight, get 100 ml of food inside him per 24 hr.
OR
2) Get some blackberry or raspberry, smash it via juicer. You need about 6 oz. Get some hay stem, cut the stem in 1 mm length, mixed it w/ the blackberry. Put the mixture in a 35 ml syringe and force feed your bun. Your bun need the fiber to survive.
You need to force feed your bun via syringe. If a bun doesn't eat, he will die, except if his stomach is suffering from bloat, then you need your vet to use the tube idea to suck the gas out first