9 yr old with behavior issues

I'm on the web doing research for ADHD or something that can help me decide if my son needs help from a professional.  He just turned 9 - he is a great student at times hard on himself if he doesn't do well - will punch himself in the face or pull out his hair if I tell him he has the wrong answer while doing homework.  He fights with his 5 yr old brother all the time and will just hit him for no reason.  

Yesterday he walked to meet me at the school yard (my kids are in 2 dif schools).  He walked with another boy & girl.  I saw him push the little girl on the ground. I called him over to address the situation & instead of coming ran around like I didn't exist and hiding behind a tree.  When I finally got there I said go apologize to her now...he walked to her said sorry & her answer was he's mean and does it all the time.  In that moment I felt heartbroken of how such a handsome young man can possibly be looked at as a bully.  He then asked to go to the other side of the bldg with his friend - I said no because of what just happend.  He proceeds to scream that I'm an iddiott for all the other parents to hear.  I was very embarrassed and told him he was punished.

We finally made it home - I put him in his room.  He just turned 9 so I took away his new Guinea pig.  Told him to stay in his & do homework there and he can come out for dinner.  When my husband got home he punished him for a month - no baseball, soccer, tv or DS.  I think a month is harsh.

Last week he was mad at me on Friday & I did go to smack him and before I could do so he slapped me across the face.  He knew last week I was upset with him yet is continuing to misbehave.

Do I call his peditrician to see what help she can give or should he speak to someone outside the house.  I feel he has anger issues.