Where is my Ben????

Ben has not been himself for the last 10 days or so.
At first I thought it was being tired from too much outside play & not enough sleep & downtime.
This boy was made for outside.
Bare feet, dirty everything.  Feet so black I can't scrub them clean.
I think he is growing too because he is eating up a storm.
But he's also been having a hard time letting go at school in the morning.
Extra hugs & kisses - - saying things like "Mommy I want to spend the whole day with you."
"I don't want to go to school today."  He's been having a hard time with his best buddy at school.
They get along so well most of the time but when they disagree it gets unpleasant fast.  I worry too b/c Ben is quite a bit bigger than his friend and sometimes they play rough on purpose.
I am at a loss.  This is so not like him.
He usually only is this way with his big sister, and that is b/c that is the way she treats him.
But now it is spilling over...and i keep talking and talking and some yelling and sometimes grabbing him to stop him in his tracks so he can regroup and refocus his energy in a positive way.
He's copying so much of Cassie's negative behavior.
I have been questioning God's decision to give us three kids.  Can I really do this?
I am a stay-at-home-mom yet most days I feel like I have no clue & am flying by the seat of my pants.
Why won't my kids obey (even just part of the time).  Why is everything a battle?
Why is it so hard to understand that the decisions Mommy & Daddy make for you are not made to be mean or annoy you but that we are looking ahead many years from now to help you become an adult who can function in society.  I am daily challenged as a parent.  I can feel the hairs on my neck raise up as I try to teach my kids manners or respect.  Or how to treat people you don't like.  It's a tough road and I know it will get harder.  Some days I am just at a loss.