*If* it is 'just' stasis then the prognosis is really good if he's getting the right treatment. The treatment sounds good, the only but that would concern me was how negative the vet was, but that may be just his personality and no reflection on his skill as a vet :? The subcut fluids definitely help me believe the vet knows what he's doing.
My buns must have had 20 - 30 "just" stasis (ie belly ache with no other underlying condition) episodes between them. All recovered with appropraite care. Both Binky and Barnaby have had the unsual presentation of very full stomach which has caused them to stop eating and they had the same treatment regime Apache is on (albiet Domperidone instead of Metaclop). Binky took a day or two to recover but Barnaby was all bright and back to his usual self the following morning. It's a mystery as to what caused it as he only had hay to stuff himself full of :? Binky, I believe, ate the contents of his litter tray which was straw based pellets, which obviously didn't pass through his digestive system very quickly and caused belly ache.
If there still appears to be something wrong tomorrow (or seriously wrong before then) I would expect them do run blood tests and do an abdominal x-ray. This especially because of the urine soaked legs - looking for kidney/bladder problems, could be bladder sludge/stones etc causing the pain. (Though very full stomach doesn't tie in with that theory).
From what you describe of his demeanour hopefully there's nothing too serious going on.