Any poop production at all is a sign of improvement – it is this time that you should be very careful.
Replace his pellets with Critical Care or Critter Be Better (powdered mix that you mix up with 1 part product 2 parts water – 1 tablespoon per 3lbs (or 1 kg) of body weight, divided up into 4-6 daily small feedings). The purpose of this is that it is very moist and slippery and if you syringe it warm, it will help to stimulate the gut to get moving from the other side to push things thru to the other side.
Fluids, given subcutaneously, are crucial, and I am assuming your vet gave your bun some of those. I know this sounds invasive, but it’s always a good idea to have some on hand at home with a syringe and needle and have a vet tech show you how to do this safely. I’ve had to give my bunny subQ fluids for a week straight once, so I had to learn.
A warm enema (about 30ml/cc) mixed with a drop or two of medical grade mineral oil also stimulates the colon to release its contents and usually when that happens, the rest of the GI tract can push the blockage through.
I don’t like Reglan and prefer a drug called Cisapride, but they are both pretty effective….If you want the Cisapride, which is what I personally prefer, the vet has to call it in or write you a prescription to a compounding pharmacy because it needs to be made up into a suspension from capsules, and since it has been taken off the market for HUMAN use you can only get it made at a pharmacy that sompounds meds. Your vet should help you find a pharmacy that can do that.
You’re doing everything you can. In the case of a true blockage, gently try to massage and knead his belly to try and “urge” the blockage thru the intestines. This is nearly impossible unless the bunny is kept well hydrated.
After bun is pooping and has an appetite again, very slowly reintroduce any pellets. make sure the pellets you feed are very high fiber, I use Oxbow they have the highest fiber content
Herbs like cilantro, served wet, usually encourage the bun to eat, and oat hay is good for stasis too. Please keep us updated.
p.s., I’ve never heard of Barium being used for a blockage before… news to me…
(((healing vibes for your little one))))