This is helpful:
A. Abdominal massage.
One of the single most effective ways to stimulate a lazy gut into action is with gentle massage. Place the bunny on a secure countertop on a towel (or in your lap, if the bunny feels secure there), making sure he can’t jump down and hurt himself. With your hands and fingertips, gently massage the abdomen. Knead as deeply as the bunny will allow, but back off immediately if he expresses pain. We have found that gently lifting the rabbit’s hindquarters a few inches (with the bunny’s head safely tucked into the massager’s elbow, and the spine firmly supported) helps gas to pass more easily, and seems to be comforting to the bunny. Once s/he gets over the initial surprise of being held this way, a rabbit will often allow his/her legs to droop in comfort and relief as the massage helps gas pockets move towards the exit.
A rabbit’s internal organs are very delicate; care must be taken to avoid bruising them and making the situation worse. After a bit of manual massage, try an electric vibrating massager. This seems to be as effective as manual massage, and it’s worthwhile to invest in some type of massager with a large, flat surface that can be held against the bunny’s tummy for relatively long periods. Press the massager firmly against the abdomen, start on low and work your way higher. The bunny may be a bit taken aback at first, but almost every bunny on whom we’ve tried massage has settled down and enjoyed the soothing vibrations. In addition to stimulating the muscles, the massage seems to help break up gas bubbles and ease colic. Massage as long and as often as the bunny will allow and enjoy.
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!
http://www.bio.miami.edu/hare/ileus.html
Like I said though, if he doesn’t seem better soon then he should see a vet.