If pipin has true stasis, he will need a vet asap to get a gut motility drug, sub-q fluids, and an anti-inflammatory like metacam, all of which will help move his gut along again. However, until then, push the leafy greens if he does okay with them when he is well, and hay. Anything you can do to get more water into his system to break up anything in his tummy that might be getting dehydrated will help. You can also try baby gas medicine to try to get rid of any potential gas bubbles in the system. Bunnies cannot easily overdose on infant gas meds like simethicone, and I have found them to be very valuable in helping get rid of gas for bunnies that are sort of eating still, but look uncomfortable and might not be pooping normally. Critical care is great for a rabbit on the mend from stasis, but until he sees a vet, it might not help much. If he’ll eat mushed up pellets, you can also try those, but I probably wouldn’t force feed anything until a vet x-rays his gut and can identify what is going on.