We can't advise you as to whether or not to give a prescription gut stimulant, due to it being prescription and the risks of giving it if a rabbit has a complete gut obstruction and/or true bloat, as this can cause serious complications.
'Like cisapride, metoclopramide is contraindicated in rabbits with a GI obstruction.
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https://wabbitwiki.com/wiki/Gastrointestinal_stasis
I would stick with giving baby gas drops, warming up if bun is cold(which they usually are when feeling sick), gentle belly massage, and encouraging movement. And getting to the vet if it's been 12-24 hrs since your bun last ate a sufficient amount, as that is considered an emergency with rabbits.
However, if your rabbits condition deteriorates, if your bun develops true bloat(belly appears distended or feels like an inflated ballon at the bottom of the ribs), and/or you have any concerns about how your bun is doing, I would recommend getting your bun seen by an emergency vet that is knowledgeable about rabbits, immediately. Especially in the case of true bloat, as this is an immediate emergency situation.
https://wabbitwiki.com/wiki/Veterinary_emergencies
If your bun is having reoccurring bouts of GI stasis, I would be looking at the factors that could be causing this. A heavy molt is a common reason this time of year, for causing digestive stasis, due to excess ingested fur and not enough fiber from hay keeping the gut moving efficiently enough to push the fur through the digestive track.
Other possible causes for reoccurring digestive problems are food sensitivities(eg. to a veggie, pellets, treats), veggies that have spoiled or have black spots, harmful weeds in the hay, ingestion of foreign material in the buns environment, environmental stressors(loud noises, strange sounds, new people or pets in the home, anything unusual or new, any new changes in the rabbits environment).
If none of these are likely or they've been ruled out, then possible underlying health causes may need to be investigated by your vet. Dental problems would be the most common health issue that could cause a rabbit to suddenly or gradually stop eating. Bladder sludge would be another common cause. To figure out what's going on, your vet may need to do a thorough dental exam, conduct blood tests, and/or take xrays.
https://rabbit.org/2013/02/gastrointestinal-stasis-the-silent-killer/
Rabbits digestive system