Do 3 year olds go through emotional stages as part of development?

[Gingerface90]

Just wondering if my DS is going through normal developmental stages. He has become very "emotional" the last few weeks. A week was due to illness but I literally can't put my finger on why he still seems to be so tearful all the time. There have been no changes to routine, he doesn't have a temperature, nothing out of the ordinary has happened, but he has gone from being a very bright happy child to quite a moody and sad one.

I am assuming this is part of normal child development but I'm not sure, he is my eldest.

Anyone else experience anything like this?