It could be that the Focalin stimulant is too much for him. Stims brought out terrible behaviors in my "ADHD" child and he had depressive tendencies as well. We tried several stims and then switched to Strattera which was a world of difference. I had a regular kid for a while until he hit the teens.
My experience is that doctors are just playing with a chemistry set in one's brain. It can be hit or miss. I really believe that my son has underlying anxiety which caused the ADHD type behaviors. If it was true ADHD wouldn't stimulants have helped is what I always thought to myself..