I also don't want to sound harsh, but you were told in posts before to expect to have to supervise 100% of the time. If he's eating rocks and you haven't seen him, how do you know? Is he pooping them out? Are you finding them in his mouth? If so, that's on you. I "didn't see him" is no excuse. You MUST supervise him better. If your attention isn't on him 100% of the time, he needs to be crated for his own safety and tethered to you in the house. If this is the first young puppy you've ever had, then you're learning too. Make it easier on both of you and watch him closely so you can reward all those good behaviors. Doing that will prevent a lot of those behaviors you don't want from ever happening.
Your other dog was 12 weeks old when you got her and you got her from a different breeder. There's a huge difference between 8 weeks and 12 weeks. I would also assume that the breeder of your female worked with her on basic manners and house training, so she came to you ahead of the game. Don't assume your new puppy is not as smart as the female. He's simply younger and each dog learns differently. As difficult as it can be, try not to compare the two dogs.
Would you mind sharing what breeder you bought your boy from? What were the conditions like where he lived? Inside? Outside? If outside, what was the kennel area like? Standing water, etc? What does the diarrhea look like? Not all poops are created equal. Are you worming him with a product from the vet or something purchased over the counter? And I may have misread yet again, but I thought you said you called the clinic on Sunday and were seeing the vet on Tuesday? If I read correctly, that was yesterday. What did the vet say? Did they do a fecal test and check for parasites, giardia, and coccidia? Sorry for all the questions, but they are all relevant to the poop issue.
