My little dog will be one on valentines day I have had him for two months he has went through at least 12 or 13 different foods he likes them when I bring them home every time but it dose not last nomore than two or three days then he will not touch anything I trade with something different and he does like it sometimes he will not keep any weight on at all he is taking vitiamins and has been wormed he is playful I don't know what I can do to help him is there any one who knows what I can do?