Hopefully Pinta or Josephine or Evangeline or Lynx can get on here and give you more advice.
He needs to eat all day. If he´s just eating mostly in the morning he is going too long without food. Could be the food in his intestine just hasn´t made it out yet. Are you sure he isn´t eating some of his poops? And the ones you´ve seen, were they plump and shiny? Or misshapened and like rat turds, a sign of dehydration.
Keep handfeeding him and syringing fluids down. Give him a poop from a healthy pig to replace his gut flora. Mash it in water and syringe down - once a day should do it while he´s on ABs.
Watch for bloat - a tight swollen tummy. If that happens, get him to a vet immediately for Reglan.
If his tummy is normal and "squishy", he´s probably fine and just needs more food.