Two year olds are like that - and it's much too early to be thinking about bipolar disorder! You might try to track what is going on when he experiences a mood change. Has he recently eaten something? Food intolerances can result in irritable moods or even normal reactions to sugar or food coloring can do that. Is he tired at the time of his mood change? Has he been frustrated by something? Although it's possible that nothing at all is linked to the mood change, it is more likely that there is some environmental trigger. Remember that kids this age don't have a lot of language skills and they frequently become frustrated at the gap between what they want to communicate and their ability to do it. Also, they are trying valiantly to assert themselves so they are very sensitive to interactions with others. If things don't go their way they can become immediately upset. Fortunately, however, they usually have just as quick a recovery. Your child sounds normal for his age. Give him some more time to see how he develops. Meanwhile, if you want to try Bach Flower Therapy for his moodiness, you might find that they help him to attain more balance and consistently good mood.  Sarah Chana