I'm not sure if he's peeing or marking, but I am pretty sure he's marking most of the time. He is an older small mix breed dog that I rescued. Not fixed. He is the only dog in our home. He is house trained, goes to the door when he wants to go out. All day, in and out as he pleases, but at night I guess he goes crazy. He almost always marks the same spot and grocery bags if they're left anywhere on the floor. This happens only at night or if I am gone for long hours. He sleeps in the bed with the kids or me. I just don't know how to stop it. Help!!