HI I HAVE A 7 WEEK OLD PUPPY AND THIS MORNING I TRIED HIM ON SOME WEETBIX/PUPPY MILK HE WAS FINE UP UNTIL 2 HRS AGO AND NOW HE CANT STOP PASSING WIND AND IS VERY LAZY , COULD THIS BE DUE TO HIS NEW FOOD? HES HAD HIS 1ST VAX.. ONLY THING IS I CANT GET...