My six month old Yorkie, Rowdy, has developed a barking habit. He just started two days ago. It's always right before bedtime and we have no idea why he's barking. I've taken him for walks, given him kongs filled with peanut butter, tried holding him and scolding him but nothing works. I hope this is just a phase. He has two older sisters here, but he doesn't seem to be barking at them. Help!!