J.B.
I feel for you--I was having the same problem last year. I even told the Dr that is was like I lost my filter and that it felt like I had the worst case of PMS ever and it wasn't stopping. I couldn't not say all these things that were making me mad. Then I would end up even more upset/angry/sad.
I finally- after a long tearful talk with my husband- went to my family Dr., told him about all of it. He said he believed I was suffering from depression. I didn't think so, I was just angry! We talked for a while (he's a great Dr like that). I took a low dose of prozac for 6 months and tried to stop taking it. Unfortunately at that time I could feel the anger creeping back so I started taking it again -on a low enough dose you don't have to be weened off. After a year I was able to stop and stay off! Aaaannnd, so far so good.
I never could put a finger on what exactly triggered everything....but taking an antidepressant really helped. Anger is a sign of depression, I didn't know it could be the only one you get.
Good luck, L.. Don't be afraid to ask for help :)