One and a half year lab throwing up now for 2 days intermittently?

My lab BJ - had a slight change of diet two days back. In that I hired a new cook and the same bread was made by a different person. It might have been a little, just a wee bit, raw perhaps. He puked it the whole thing Monday evening with bile juices. Then the next day he puked his morning meal again. And some biscuits. I gave him some medicine (gastroesophageal reflux disease (GORD/GERD) medicine) last night so he kept down his morning meal today. Again, this evening, he puked out the boiled rice. He is a bit lethargic though not completely tired. I am calling his vet today - but am a bit worried it could be poisoning? Any experiences? Anything I can do to make him feel better in the meantime?