I also have a 7 yo chocolate lab who does it also. The pills didn't work for him either. Prob b/c we didn't give them to him long enough. I'm not sure if they are eating each others stool or not. I guess we will just have to stay out there when they go & p/u poop as soon as they go.
They all seem to grow out of it. I had that issue with one of our adult dogs, and two pups from the previous litter. It was gross and I kept the yard very clean, but they always found some to eat. Our pup is now 7 months old and she has stopped. I guess you could always muzzle when out in the yard if they had to be there for a longer period of time.
He is your friend, partner, defender, your dog. You are his life, love, his leader. He will be yours, faithful and true, to the last beat of his heart. You owe it to him to be worthy of such devotion.