This,too, shall pass. My boy went thru this stage. Know I spent at least two months digging thru poo. Never found where he passed any rocks, aluminum or plastic I thought he had swallowed. The plastic milk jug and beer can he came by with had chewed out sections, never found them in the house. So I assumed he swallowed them. It is a stage of exploring and all they can use is their mouth, so everything goes in, but not neccesarily down. You have to be careful the pup doesnt turn it into a game of keep away cause that is when things can be swallowed. I used distraction with a toy, food, whatever will get your pups attention and cause him to forget and drop the rock. Meantime start teaching him to drop it and leave it during training times. I will say I called my vet in a panic one nite wanting to bring Parker in and he had me to wait it out. Saved me $100 after hour fee and Parker did throw it up or that could be one of the poo digging missions. He did throw up a rock once. Best wishes!