My Penny - again.

I apologize if I am being a pest about this but I can't figure it out and it seems the vet can't either. Penny is taking reglan and tagamet for vomiting. She eats and then vomits (actually, I think it is regurgitation). For a few days after she started the meds she did very well. But now almost every time she eats, she vomits. I will be calling the vet again tomorrow, Just wondered if anyone had any ideas. Thanks