biting help

Over the last 8 months I've seen my very active 2year old become aggressive. It started with "strong" hugs, then hair pulling, and then the biting started. My husband and I stress daily the importance of being "gentle", and have even started "time outs". When an incident occurs, my son genuinely seems shocked that the other child is sad or hurt. So I know he isn't trying to be mean, he just doesn't understand what he's doing. Our pediatrician told me that some of the bits were "love" bits.  That he just didn't know how to handle the surge of emotion he was feeling.  So we working of gentle kisses.  Things seemed to be getting better, we went about month without an incident, and then on Sunday, when frustrated that another boy took away his toy he bit.
Due to his increased aggression I'm finding it harder and harder to go to playgroup. I'm so worried to leave my son's side in fear that he may hurt someone and I feel embarrassed that it's always my son who caused the scene. I know that all the other mom's in my play group see my son as the "mean" kid, and worry about their child's safety.  We've stopped going to church because I'm afraid to leave him alone, knowing that if someone isn't right there someone will get hurt. I don't want my son to be known as a bully, because he really is the sweetest boy. I'm just at a loss of what to do to change this behavior. Does anyone have any suggestion?  Do I need to take my son to a behavioral specialist?  
One last thing...I am expecting our second child in April and wonder if this is also contributing to his behavior?
Thank you so much

[Kevin Kennedy, Ph.D.]

You are over-reacting to something that could be expected. That is, his behavior is not going to stop overnight. He had gone for a month without biting - you can see you are on the right course. Simply because he displayed another episode of biting is not reason to be alarmed. Keep on a consistent path - that is, immediately when any type of aggression occurs, place him on his time out chair for five minutes. Be consistent in this approach. You are wise to supervise him carefully at this point. But I can hear the emotion in your note. There is no need to become emotional about this. It is just behavior and you will manage it fine.