The typical method for fighting bad gut bacteria is to introduce good bacteria. One way is Bene Bac probiotic powder. The other (better) way is to get your rabbit to eat more hay, since hay encourages the growth of good gut flora. For the powder, it's one pinch worth of the powder per day for about 7 days. One method is to dip one end of a food item into water and then into the powder and feed that to him.
I don't suppose you could post a list of what foods (and quantities) he was given just prior to his gas issues, could you? (Has he been grazing on wet lawn grass by chance?)
If your bunny's gut actually did hit full-stop, then you'd want to get him to a vet pronto. Here's what was done for a rabbit I know recovered successfully (note: the stuff in the following regimen is not the kind of stuff you'd regularly give a bunny. It's only for emergencies):
http://www.blitter.com/~nebulous/otherworld/Rabbit-MotRegimen.txt
I have given him Beve-Bac Plus since yesterday, and I will continue to for the next 5 days. I have Critical Care on hand to help him if his gut did stop, I just don't want it to get that bad because I will probably die from stress.
So since this all started in January I will tell you what happened:
It was the 2nd week of January and I decided I was going to start introducing more veggies into Theo’s diet. I made a long list and got busy shopping. He did great that week. The next week my parents didn’t take me to the store because they thought I was making a big deal and that he didn’t actually
need veggies, and that I just wanted him to have them. They were so wrong, but I made use of the veggies that we had in our fridge. I think I gave him too much Bok coy because he started acting sick. At the time I didn’t know that though. I had been grooming him that day and I thought that maybe the stress from the nail clipping had caused him to get sick. He was sitting hunched up and I had never seen him sit like that ever before. I panicked and posted on here:
https://www.rabbitsonline.net/threads/help-weirdly-shaped-poop-territorial.96989/.
We took him to the vet, and they took an x-ray. He had a full belly but no gas, so they didn’t think it was stasis. They sent us home with Reglan and said to give it to him for 4 days, and that he should be completely better after 2 days. But he wasn’t. He was still sitting hunched up 3 weeks later. It was when someone suggested taking him off all the medicines I had been giving him. It worked and he was better, but only for 1 week.
The week he was healthy he got ¼ cup of pellets, unlimited hay, and a handful of clover from outside. Before I knew it I was dealing with a sick rabbit again. I gave him gas drops, Reglan, and some veggies. This time it got so bad he was not eating, and I had to force-feed him for one night. That is where this thread picks up. It has now been 6 weeks since that week when he was healthy.
Sorry, this is so long, but I just thought I should tell you the whole story.