dog goes crazy when son leaves for school

Question
-------------------------
Followup To
Question -
Our 2-yr-old dog, with herding breed in her mix, has developed very bad habits in the morning when my 13-yr-old son is leaving for school.  Here is the routine as it's supposed to work:  son wakes up at 6, showers, dresses, eats breakfast usually with TV on.  He goes upstairs to brush his teeth, collects his things, and leaves the house shortly before 7.  Preferably the dog would ignore this routine.

Evidently we have done something that encourages the dog to get overly excited when my son begins to leave.  As soon as he gets up from the breakfast table, she starts barking and jumping at him and nipping his heels.  'Off' command is disregarded, as are 'Sit' or 'Come'.  Over the last several months I have tried several different approaches:  I have tried to intercept the behavior by leashing her before he starts to leave and taking that opportunity to reinforce walking on the leash, sit, down, and speak commands (with treats).  I have tried positioning her behind me so I am between her and my son, so she should not feel impelled to control him.  I have gently forced her into a 'down' position and held her there.  Throughout any of theese efforts we have barking, yelping, whining, and frantic attempts by the dog to get away from me and to the boy.  With all this going on, I cannot speak to my son, let alone give him a goodbye hug for the day.

Normally she is well-behaved and responsive to commands.  Other times during the day, or when the whole family is around and we are leaving to go somewhere, the dog is fine.  At those times we all get ready to go, tell the dog to go to her room which she does without a problem.  (I tried to mimic that routine in the morning too, but she wouldn't settle into the room the way she usually would.)  

What approach do you suggest?  Unfortunately the school year is soon going to end, but I expect the behavior to return next September and if I can at least begin to train away from the behavior now I will have a head start.
Answer -
Hi Gwen.  It certainly sounds like you've tried to take all the correct approaches to controlling the behavior.  I just have a couple of questions to clarify a few things to hopefully come up with a plan of action for you.  Is your dog crate trained?  Who is responsible for her day to day care, feeding, walking?  Is she exercised on a regular basis and by what means?  If you can get back to me on those few things I can certainly try and come up with a solution for you.  Thanks!

Shawna, the dog has been crate trained though I am not currently using it because of space constraints.  I am the primary caregiver, with other family members assisting occasionally.  I am home with the dog most days.  She walks with me and my 8-yr-old daughter to the bus stop (one block each way) about an hour after my son leaves.  Later in the day, weather permitting, I take her for about a mile walk and sometimes spend added time playing with her in the fenced back yard.  She is a small-to-medium dog, about 22 pounds.

Answer
Gwen, I haven't forgotten about you.  I'm doing a little research on your situation and talking to a couple of other trainers about your girl.  I want to be able to give you some solid ideas.  Thanks for getting back to me with that information.  I'll be in touch soon.

Shawna