adult dog urinating in kennel

We are currently fostering a one year old lab mix. We don't know his history except that he was an owner surrender. We have two other dogs in our house that are our own. The foster is SUPER high energy and his main goal in life seems to be counter surfing. We've had him almost 2 months. The first few weeks he was fine. Last week, he started having accidents in his kennel over night. He also started peeing as he walked in the house. We took him to the vet and they ran tests. He's fine medically. He wakes every night in the kennel and cried to go out. Last night my husband let him or at 2 am. Sometime between 2 and 5 am, he had an accident in his kennel. I'm at a loss. Any ideas? I feel like I'm not getting any help from the resuce