How long has it been since he ate? Is he refusing all food, even his favorite treats? Did he have digestive slowdown, or smaller poos with hair in them over the last few days?
If it has been 12 hrs since a bunny pooped or ate, I would consider it an emergency.
I would get some simethicone in him, as well as some water/pedialyte. 1ml of baby gas meds is a good choice. It can be given once an hour for 3 hrs, along with 5ml/hr liquid at least, with tummy rubs and access to a heating pad (for the belly pain). If you have left over metacam from a spay/neuter, that might be good as long as it is less than 6mo old. You can also have a listen to his belly for gurgles.
Check for other signs of illness, like cold/hot ears, lethargy, hunched position. If he becomes lethargic it is definitely an emergency.
