I am having trouble getting my dog to eat?

I use to feed my dog the royal canin puppy food and when he had two teeth pulled i had to switched him to soft food (Cesar's) he loved it and never wanted the dry food again. I went on vacation about two weeks ago and when I came back I could not get him to eat the food, so i brought the beneful prepared meals and he loved them for a while then he refuse to eat it. I then give him the chef michael's canned food and it was the same as the beneful meals. I just switched him to puppy chow dry food and he loved it at first but now he will go all day without eating and will only eat it as a last resort. My friend swears they didn't give him table food while I was gone and neither do I but it worries me that he doesn't eat because he is only a 7lb maltese/yorkie mix. Sorry this is so long.