Hey, so I understand what you're trying to say I think...
It's easy to get confused between cause and effect of moods vs situations, I've tried to figure it out and the only conclusion I've come to is that even though it may feel like I'm reacting to an outside element when my mood swings wildly, more often than not I can find myself making "excuses" to be in a certain mood (or making it easier for myself to get carried away by my mood) E.g. I feel kind of angry or restless... my BF does something that I maybe don't agree with... I fly off the handle... sometimes I've noticed I'm just waiting for these situations so I can vent some "bad" energy. Same thing happen when I'm depressed. I think this accentuates the mood changes and does leave you feeling like you maybe caused them. When I think about it more, the underlying energy type (sad/angry/agitated etc) is always present before I make something of it.

Kind of like everyone said above, I've been trying to learn to accept a thought that comes to my mind, and then try and let go and move on from it. Harder than it sounds though!