What do you do with a heavy heart?

What do you do with a heavy heart? When you feel burdened down and sad and don’t really know why you’re feeling the way you’re feeling. I’m a very analytical thinker and like to have everything understood and compartmentalized. I don’t understand why I’m feeling the way I’m feeling today. I feel incredibly sad. I don’t know why. This really bugs me. I’m using a large part of my brain energy to try to figure this one out, which has made me distracted and irritable today (not a good thing when you’re towing 2 distracted and energetic children around from church to family gathering and back home again). I think I’m hearing God telling me to stop striving. That’s really hard to do. Leave a mystery unsolved? I don’t think so. But my analyzing and over-analyzing is not getting me anywhere either.