Hello and welcome to MedHelp's forums. Since you have a family history of Bipolar and mental health concerns, it is wise to be observant of your children to look for patterns of also having such things. That is being a good parent and I commend you for taking this into consideration. This could be signs of bipolar but also could be normal childhood behavior. Here is some information on bipolar in children and what it might look like. https://www.nimh.nih.gov/health/publications/bipolar-disorder-in-children-and-teens/index.shtml. The word 'extreme' is used a lot. Most kids can have moods, say things and flip the switch but with bipolar, as you probably know since you have it yourself, it is much more intense and drastic.
You should mention your concerns to your son's doctor and if they feel the same as you do, then a referral to a child psychiatrist would be the next step. Please let us know what you think.