Why do I feel like crying?

Lately, for no apparent reason, I have felt the urge to cry. I can’t bring myself to cry unless something actually causes me to, but that feeling is there. And then, when something does cause me to cry, I snap and start bawling. I have never felt this depressed and on the verge of crying this much. I have depression, but it’s never been like this. Also, as far as I am aware, (other than the usual school stress/ being an adult and feeling like I need to run away because I don’t know where my life is going) I don’t really have a reason or anything that is causing me to be upset. Should I be concerned?