Baby treats

How many yogurt melts / puffs do you give your child a day? My son is 11m old. I seldom give him treats. But my brother keeps giving him whenever he sees him. Like 5melts and 5puffs after every feed. So its 15 each a day. I do not like it, and yes, i did tell him every time! But it doesnt stop him from secretly feeding behind my back. My son has been eating less solid these few days, ever since i moved in with my brother. Is it because of the treats or just a 11m thing that he isnt eating well now?