Constant crying 4yr old!

My step son cries over everything. He is 4 and can cry any minute over anything. Two years ago my husband and I got custody of him and his sister. He was 2 and she was 5. I have been in his life since he was born and her life since she was 2. We were getting them both every other weekend before we were granted custody.  Their mother is not around but twice a month and all visits are supervised. She is not a very good person.
My step daughter is the perfect child, no problems, straight A student, never in any trouble. He on the other hand stays in trouble! He hits, punches....etc. He also seems really sad most of the time. He will cry for no reason at all, example last night I asked both kids to clean their room and when they were done they were to help me. She finished and came and helped me. He took forever putting his toys away, so when he was done, it was time for dinner, he cried. This morning he cried because he wanted to watch TV at his baby sitters, no one ever told him he could not watch TV. He will also cry when he is happy. He won a big event this weekend and cried over that. He also seems somewhat lazy...I know that seems like a crazy statement about a 4 year old, but he will not run with the other kids, just walks. He wants to watch TV not play outside (I do not allow them to watch more than an hour or two a day). We are a very active family always outside. We have a ranch with horses and cows. We ride horses, hunt, fish…etc. He would rather lie around and do nothing then play.....I am so confused. His sister is just the opposite, loves to play, run, and is super outgoing...I am so confused, and worried by this and the crying...should I be concerned? Is there something I need to have him tested for? Who do I talk to about his behavior?

[Kevin Kennedy, Ph.D.]

Yes, there is reason for concern. His symptoms indicate emotional disturbance and invite evaluation by a pediatric mental health clinician. If you don't know where to turn, ask his pediatrician for some guidance about a possible resource.