Bipolar

I feel like all children are bipolar.

Really, they are, it's my conclusion.

My child can go from super happy to full on tantrum in a matter of second and then back to happy like nothing ever happened. 

What?

I am not sure how one does this.

Now I can go from happy to crazy in a matter of seconds but I haven't quite master the going back to happy like my child has. 

Example: today we are trying to my moms house and he is all happy talking to me while we listened to some music that was on very low. Out of no where, instead of asking me to change the song because he doesn't like it, he flips and starts screaming, yelling, crying and trying to get out of his car seat because the music was making his "ears bleed" not kidding. Then after what seemed like forever but I am sure was only a few seconds maybe a minute he was completely back to my normal child singing and talking to me like nothing ever happened. What!?!?!? 

I am left so confused after episodes like this and leave me with too many questions.