Sudden urges to cry

I don't know how to explain it or why I even feel this way but sometimes I get this really weird feeling almost like I'm completely exhausted(but I'm really not) and just want to cry for absolutely no reason at all. It happenes randomly and it makes me really upset. I've never experienced this before pregnacy but it's been happening a lot lately. Has anyone else experienced this? Know what it is? Or why it's happening? I know my hormones are going crazy but I don't even know if it's that and what category it would even fall into. It's driving me crazy and making me feel depressed even when I have no reason to be.