My 3 month old was left with our neighbor while we were out of town for 5 days. He has always been very hyper and destructive. When we returned and brought him home, he has been coming in the house and just laying down. We have a cat he likes to go after but doesn't take much interest with it anymore. His eating is normal and still plays with his toys..just not the same dog he was when we left. Could anything be wrong with him? Should we worry?