Why do I feel so angry and violent all the time?

There is a part of the brain called the dorsal raphe nucleus which is one of many pathways that regulate serotonin and may possibly be the cause of your recent anger. There is the ventral-lateral part of the dorsal raphe which corresponds to the prefrontal cortex which may not be getting enough serotonin or the Interior part of the dorsal raphe which regulates panic may be getting too much serotonin. Usually SSRI's (antidepressants) could work or you may want to go to the doctor and see if they can do something about that. It could even just be stress. Working out releases serotonin in the right kind of areas that make you happy, so try that and even smiling has been shown to reflect in the mood of that person, even if you just smile for no reason. :-)