My Doberman has been acting weird lately?

My male Doberman is around 6 years old. He's a healthy, active, amazingly friendly dog. But lately he's been stressed about something. Since last week He cries every night now and roams the house. He's completely restless. He's not as interested in things as he used to be. He has an ear infection and sores on his paws from playing to hard, so I'm thinking maybe that could be it. I've been treating his wounds for about three months, but he's never acted this stressed. I'm not sure what to think. I really am getting scared that it's old age. I don't want to lose my bestfriend /: anyone know what's going on? Thanks, much appreciated!