Tell us what you feed your rabbit on a daily bases?
I would push fluids, offer water in a bowl with some fresh pineapple juice or apple juice to encourage drinking, to make sure your rabbit is fully hydrated. Rabbits digestive systems slow down if they become dehydrated for any reason.
If you think it is gas, you can get infant wind drops, infocol, simethicone from pharmacy or grocery store.
The dose for simethicone is in this article which also has lots of good advice so you should probably read the whole thing.
http://www.bio.miami.edu/hare/ileus.html
B. Simethicone
(liquid, pediatric suspension or tablets) is essential for the relief of gas pain which usually accompanies ileus. For relief of acute gas pain, 1-2 cc (20mg/ml suspension) can be given as often as every hour for three doses, then 1 cc every three to eight hours. This substance has no known drug interactions, is not absorbed through the intestinal lining and acts only on a mechanical principle: it changes the surface tension of the frothy gas bubbles in the gut, joining them into larger, easier-to-pass bubbles. Simethicone is practically inert, and is safe to give, even as a precaution, as long as it is not given long term. (Note: liquid suspensions of simethicone are relatively expensive. Less expensive versions, such as 125mg gel capsules are equally effective. A bunny can safely receive the contents of half a capsule at the rate described above.) A flatulent bunny is a happy bunny!