My baby boy refuses to suck. He was born on 9/...

My baby boy refuses to suck. He was born on 9/2/06 at 38 weeks by c-section weighing 5340g (11 lb 12 oz). I am an insulin dependent diabetic. He won't suck on breasts or bottle. He sucks on a dummy ok. It is a strong suck but not continuously like it should be. As soon as I put the bottle in his mouth he either gets upset or has a few sucks and goes to sleep. some days he will also gag on the dummy too and he also vomits a lot. He is being tube-fed nasogastricly in hospital. He has all the doctors guessing and running various tests but they keep coming back as perfectly normal. Has anyone encountered anything like this or heard of someone else in this situation? I would really appreciate some feedback/suggestions. Nobody so far has any ideas. I just want to finally take my baby home.