C.H.
I recommend you go to your pediatrician first. I have a 4 year old and a 4 month old. We have been trying to get into a play therapy or counseling session at Lena Pope home and are on a 2 month waiting list...which I hear is about right. The pediatrician said my son was already strong willed but more so now that the baby is here. She said he was resenting me. My son even told me he missed the days we used to play together. I tried sending him to a PDO for 2 months (to give him his own learning experience and me a break) but that didn't work out.
If you would like to email me, I would love to share my experience. I have tried everything from behavior charts to rewards of time (black balls in jar with rewards of slumber party with dad, etc which we just started and he loves.) I include my son in everything I do (one of his chores is filling the diaper bin) for the baby and he loves helping. I think it is all about making the adjustment. My husband is only here on wkds (busiest time of the year) and dotes on him the entire time. My son used to prefer his daddy (good cop-bad cop) to me but it seems the more structured I am during the week, the happier he is with the situation. He loves his brother but in the past used to bite him to get my attention. Sometimes he gets angry with me when I send him to time out or ask him to do something he doesn't want to do. Even while I was pregnant, he would try to hit me or bite me when I sent him to time out. I had to become very firm and stopped this immediately. He is very strong and I could just see him at 14. More to tell...good luck. My son is a sweet boy and I know we will get through this.