Why do I have these mood episodes?

Hi everyone, I'm new to this forum. I'm not really sure if this is the best place to ask the question, but I'll give it a try. The other day I felt very spaced-out for no particular reason, No tiredness, no hunger whatsoever. Suddenly, I felt extremely sad as if I just wanted to burst into tears... Then I wanted to laugh. It sounds crazy. But it's frightening. I've had these feelings (not frequent) but I have had them over the years. Will this go away on its own? Why am I having this?

can't really answer this with more than a guess but sometimes i space out and then start feeling really rubbish later.. I think for me it's because there's a lot of stuff going on that i'm just not paying attention to.
I spend so much time and energy just pretending to be okay to people, that i forget to deal with my real feelings underneath the public ''yes i'm fine, how are you?'' - then when it builds up to a really high level, i zone out because my emotions are too strong to ignore - the zoning/spacing out are my brains way of closing off anything non urgent so it can try and deal with the emotional stuff i've neglected.

Do you think it's possible that something similar is going on for you?
what thoughts were going through your mind when you felt like bursting into tears?

another thing i'm wondering is.. what were you doing when you spaced out? could what you were doing have negatively affected you but you didn't consciously realise.? (I get it a lot when i'm on facebook, reading through posts from family members that i wish i was close to but can't be due to wider family issues)

Yes I feel the same. It's hard to pretend that I'm okay when I am with people. Sometimes I feel alone even though I'm discussing things with the group. When it's not my turn to talk I feel like I am an outsider and I feel insecure. I tried to hide it and avoid dealing with it because I tell myself that it's not good to dwell in self pity and other negative thoughts. Do you think that I've reached the peak of my controlled emotions and I am breaking down even though I don't want to? Small things make me cry like touching pictures, headlines, movies, typo errors,etc. The laugh is just hysterics I think.