Madden is about 8 months and he's 3lbs. He won't jump up onto the couch or onto the bed even with a bunch of pillows to help him reach. The other two yorkies jump up on the couch, bed, pretty much everywhere and Madden just sits there or puts his paws up on the couch (he wants to be picked up). I don't know if he's scared/timid or if there could be something wrong with his legs. Anybody else have this problem?