
Hi, First thing to do is make sure he is not dehydrated. Pinch the skin over his withers or on his shoulder, if it springs back at once, no problem, if it stays "up" for a second or two then he needs re-hydrating. Lectade or Diaoralyte given by a bottle or syringe should help. Remember that if he is dehydrated he cannot process the milk you are giving. When I have a puppy who is noticeably doing less well I like to bottle feed as this lets me see exactly how much the pup is taking, rather than relying on it's ability to cope with suckling from Mum. The secret to success is little and often, especially with a weaker pup. As soon as you are satisfied he is gaining weight and loking strong he can then be put back on Mum.
If her milk flow is still not up to expectations I would take her to the vets for an Oxtytocin shot, which makes the milk come down. It is fine to do this even after a C section.
bye
Gwen