My Dog Was Fine, Happy And Running Around At 1:30PM,

My dog was fine, happy and running around at 1:30PM, I CAMe HOME FROM WORK AND SHE IS LISTLESS AND noticed she threw up her food. stood up to greet me and then just layed back down. I got her to drink some water, eat a chopped up hot dog and go outside. She urinated and pooped, looked normal. Now is still want to just lay there and doesn't wag her tail when I try to get her to. She is 12, golden retriever. should I take her into emergency