I've had this happen to me at work and it's very distressing :/. I think it's the stress of the job that causes it in me. For me, I learn to recognize when I've had enough and leave. Sometimes it only hurts you to stay and continue feeling emotional. If it's not too bad I'll use distraction, try tackling an easy task you know you can do. It'll give you a sense of accomplishment hopefully and you can ease out of the overwhelmed state!