My Black labrador Ollie is nine months old and last week we took him to the vet for vomiting and he was diagnosed with Gastrientitis (Stomache bug) He got anti-biotics and a booster injection and wasn't sick again but some mornings when he gets his breakfast (Wainwrights chicken and rice) he jumps away and makes a face like it's just bit him! He does eat it but he was just sitting eating his dog bone and he went to get a drink and came back and went to pick it up and done it again and didn't stop. I don't think its associated with his sickness because he only does it sometimes.

Try a different bowl/food/location.
Maybe something was in his food and bit him?