The title is probably not worded the best but I seem to have this happen anytime I don't "stay angry" for a long period of time. It's like being pricked every 3 seconds with this very loud thought in your head, and you start to get annoyed at the fact your brain is constantly reminding you of that situation. Sometimes, I find that if I was only pissed off for a moment or two, I can get past it by sleeping. Other times, I lose the fight and end up upset indefinitely until the next drastic mood change.