I have crying fits too, pretty much all the time.
I am still really new to all of this; my master is the only person who has ever seen my true potential and shown willingness to unlock this. I want to learn so many new things, not just to please my master, but to prove to myself that I am capable of such things.
When it first started, it was through the pain of an intense flogging. I would try my hardest to hold back my tears of pain, fearing I would disgrace myself by letting such emotions show, but eventually I realised that to do so was, for want of a better word, pointless, and from then on just gave into it whenever I could feel it coming on.
But then, after we had been together a little while, I found tears of a different kind beginning to form. I have a tendency to get over emotional as it is, and this started to come through in an overwhelming confusion of feelings, during more intense sessions, or sometimes not starting until the session was over. I soon came to recognise it as a form of emotional release, as once the tears dried up, I always found that I felt at least a little better.
There is no shame in crying during a session, in feeling emotional. Do you feel anything negative while tearful, any panic or fear? Do you, like me, feel better for having had a cry? I wouldn't say, at this point, that there is anything wrong. In fact, my master gets off on my crying, when it's tears of pain. He loves to see me push my limits, and endure just that little bit more pain, and when I do, he is extremely proud of me; he once told me that my tears of pain are 'the icing on the cake'.
Have you spoken to your dom about how you feel, does he/she understand what is going on inside your head at that moment? Communication is vital, and a safeword or safetoy is also a good idea, to end a session that gets too much for you.
Hope this helps
