Hi Yorkiegirl, have no experience of this, but have used DH's very good search engine that he uses for research.
It seems that a baby vomiting bile indicates either a gastrointestinal obstruction or possibly a twisted bowel. These problems can sometimes require surgery which generally resolves the problem.
I don't know if this helps to relieve your worrying but he's obviously in the very best place at the moment to try and sort out what is going on. Keep us posted.