I am not sure how much your puppy weighs but generally I would not consider a little yogurt as a cause for diarrhea of 3 days duration even in a very small dog, except maybe in the case of lactose intolerance which is possible at her age. Since she feels well you can try simple home treatment for a day or two but if the diarrhea persists after that let me or your vet know. Give her 1 teaspoon of pepto bismol or kaopectate per 10 lbs of body weight 2-3 times a day for a couple of days. Continue the bland food during this time also.