cheryl,
If vernon vomitted again soon after milk feed, then it's the milk. Try give him porridge or something else (eg fruits, bread, biscuit) without any milk product, if he is okay, then confirm is the milk. Call you PD and tell him/her this, ask if it's advisable to change to isomil temporarily for vernon. It's okay, don't worry so much, as long as he is not dehydrated, it's okay. My believe is as long as one is able to vomit or poo (diarhaera) means good, cos the body is reacting to the bad things and try hard to get rid of it from the body. Last time my boy the first night, one night only vomitted maybe more than 10 times!!! Just have to make sure he is not dehydrated.