I would take him back to a vet that does a little more than induce vomiting. A vet should do a barium test and look at x-rays to ensure that there is nothing ingested.
My 9 month old dobe got into my pills the other day ( i think 2-3 days ago ) i rushed him to the vet, not knowing if he ingested any. They used eye drops that induced vomitting, however, did not find any pills in it. He was fine that day (ate as usual) and was fine yesterday. This morning he began whining a lot and had a lot of diarrhea..mustard like color and very watery at times. He vomited in his crate. Do you think this is from the other day at the vet? Even though it's two days later... yesterday I sprinkled a little parmesean cheese on top of his dog food, but I used to do it all the time when he was younger and he never had problems. These are the only two changes that have occured in the past few days. I tried pumpkin and boiled rice and chicken but they have not helped with the diarrhea. Any other suggestions? Breaks my heart to see my poor Rudy sick.