I tend to waiver on the side of taking a peek into the environment, overall past history as probable cause to emotions that feel extreme and over the top. Meds can certainly help, the biological factors. Some triggers may not be as obvious as they appear. Therapy, self driven therapy, over time, as long as it takes, peels away the surface. Aside from the therapy and meds, are you active involved in any support groups and immersed in any self help literature?
Anger can oft be root of feelings of injustice, frustration, trapped feelings, etc. It comes out lashing in or out, when unable to articulate the root source.