Hi LaMa, in some branches of psychology, there is a concept of sub-personalities. You know how some days you just feel like a different person? You may move a little differently, think differently, have a slightly different way of talking or seeing the world? Do you have days where your thoughts are not aligned with how you normally think and feel? Well, in psychology these different states are considered metaphorically cut off parts of yourself that are probably developmentally younger and that need to be accepted, nurtured, and integrated into your dominant personality in order for you to become more whole and more complex and emotionally rich and balanced. The society generally rewards the more driven or success oriented parts of ourselves, or the more easy to get along with traits we have. So often we stuff the sad or frustrated parts of ourselves down, and they become part of our shadow, and those parts don't have the chance to come out and express themselves, and generally don't mature very much as a result.
I think you could be releasing a lot of pent up sadness or frustration or any number of repressed emotions, and to me this could very well be the healthiest thing you could do to just sit and cry and let the feelings out. We can't heal and grow if we are constantly stuffing the unacceptable parts of ourselves down. It can be painful when these parts resurface, but it's also healing and necessary to be a strong emotionally intelligent person. I have done a lot of work on myself in this regard, and I still have a very long ways to go.
This is only my guess as to what may be happening, but I thought I'd put it out there and see if it resonates.