mine had this too
my recommendation is they have to be on fluids for 72hrs at a facility and no food or meds through mouth as it can be a problem as the vet did same for us and my boy relapsed and almost died. I would call an internal medicine specialist and discuss 24 hr care for 72hrs as any food or meds through mouth can be painful and upsetting to system - it is very painful as well so they need pain meds and why your baby is in pain when you touch the belly