My 2 year old dog has been puking lately, do I have to take him to the vet?

My 1 year old cat has done that before. She threw up soon after she ate her food but she was perfectly healthy. We changed brands and that stopped the vomiting. It would be best to take him to the vet but if moneys a problem just keep an eye on him, if he keeps vomiting or shows signs of pain or just strange behaviour take him to the vet