I hope Benji is better this morning. Dogs can get things like this just by something they have eaten (that perhaps they shouldn't have) just like we do. I am sure the antibiotics and the injection will help, when they are able to get something to eat then very light meals helps. When Milo had something like this he was on light meals for about a week, just so his digestive system could get back to normal. But go with what your vets have said to you, they know Benji.

Margaret