Help my puppy rottweiler is ill he is 8 and a half weeks old and has been to ill to have his injections?

my puppy rottweiler is being sick bile and has got diarrhea and is very lethargic he has a hernia which the vet has said will be fine so there is no need to worry about it as long as we keep an eye on it he hasnt got a fever at all his temperature is perfectly normal but he wont eat and i cant understand whats wrong with him and the vets arnt sure either he hasnt got any blood in his diarrhea either he is at the vets beng treated and doesnt seem to be getting much better has anyone else had this problem anyone got any ideas on what it is?? please help