Ok, so the first few days my green cheek conure was great, didn't bite or anything, now whenever I put my finger even near him he bites, and bites hard. It's not a nibble at all. Sometimes he will bob his head up and down (Is that a sign of aggression?), and I can't touch him without getting bit. What should I do? He's not trained to step up so I can't do the ladder thing..