I never can feel something unusual, takes quite some experience and the right circumstances I guess - but since that is practically a belly massage it might actually help.
What I do when this happens is that I make the rabbit move, keep it hopping for half a minute or so every now and then. Or I give belly massages, actually I put the rabbit on my leg, facing me, and rock the whole rabbit for some minutes and pet it thoroughly. Sometimes this helps to get things moving again. I repeat it every hour or so, every two through the night.
I also give simethicone - baby gas drops, at least 20mg per serving - , either mixed into a little kitchen oatmeal if the rabbit still eats, or mixed in water with a syringe. If the rabbit hasn't eaten for 6 hours i syringe feed some water, and some painkiller.
And I try to make them eat. Holding some hay against their nose until they bite into it out of anger sometimes works. I have dried stuff for such occasions, willow and apple leaves, nettles, butterbur. Even in winter blackberry leaves, narrowleaf plantain etc. can be found.
If nothing works for a night I'm off to the vet ASAP.