My DS did this for about 3 days after birth, but he was mainly vomiting up blood (and once.. gross... a pubic hair!???!!) anyway, he had a terrible tummy ache for the first few days from it, didn't feed at all, but once he got it out of his system, he was fine, and began to feed well (they did give him formula twice in hospital as they were a bit worried about him, but he wouldn't have that either)..

Try holding him tummy down across your lap and pat him gently on his back to try and get it all up and out of him.. and put down lots of cloth nappies or you will be changing sheets constantly!

We always say DS will never be a swimmer unless he can learn to keep his mouth shut!

Good luck.