Dear W.,
I am a Mom [I was widowed with children 14 yrs.to 20 months old] and now a grandma also. Firstly, you have to consider his age. There are stages that they go through and this is one of them. May I throw some thoughts out on eht tablefor your consideration;
You are a teacher and if you are away from him alot,this may be a response to him needing, not just wanting, more of your time. Why I say need, is that in each of us there is a need to feel secure. He has a younger sibling and that is threatening to the time he gets with you and if you work, it is added to. I do appreciate how busy you are but maybe try giving him one on one time or maybe a day that is just for the two of you or a shorter time.
Reassure him contstantly how important he is to you and tell him you love him constantly.
2. I went to a parenting conf. one time and a lady said a very interesting thing about 'time outs'. When a child does something that upsets us and we send them to their room or a spot until they or you get under control, we plant in their subconscious that you are not a safe place to go to when things are wrong. When they become teenagers, etc. and they don't come to us with their problems, we wonder why. Because when they were little they had to go away from you when there was trouble and why would that change when they get older. It is very thought provoking.
I do not know if you have a religious background but I will put this out to you anyway.
When we are in trouble, The Savior never says to us Take a time out until you or I get ourselves under control. He always says "come unto me" Take your child on your knee, hug them close and tell them that you are sorry that there is a problem. This may seem hard to do at first but with practise you will see the changes. You are not condoning the action. Correct the problems but especially when they are this small, build a relationship with that child that all the evil forces in the World will not penetrate because they grew up knowing Mom is a safe place and a good place for fair and balanced correction. The bonds of trust will last forever and their teen years will be far easier on them and you.
I wish that I would have heard that advice when all my babies were little. Include The Lord in their upbringing and if you can't be there for their upbringing He will always be.
Hope this helps.
D. M.