Weird anger-related phenomenon

I am 34, male, single. I've been diagnosed with "emotional immaturity" and very high agreeableness.
Since the age of 16 I have experienced a weird kind of anger attacks. Sometimes I go through entire months without having one, but this month I already had two.
During the attack I start seeing reality as very ugly and experience a lot of aggression and destructive thoughts. This thinking can have strong religious components. I'm not currently religious, but I was a very serious Christian in the past, and in my fantasies during the attack I sometimes see myself as a crusader.
Sometimes I also feel as if I had fever. After the attack I'm very tired.
Many of those attacks happened after a friend let me down, or someone treats me unfairly, but others happened without an obvious cause. I've talked to a psychoanalyst about that and he said that I don't express anger openly, but store it inside, so eventually my subconscious has to discharge.
So why cannot I get angry like a normal person?
Also, can this be a symptom of a serious mental disorder?

Hi,

Did you continue seeing the psychoanalyst? Sounds like you have anger issues and yes you could be struggling with mental health illness. But you could overcome it since you are open and you seem to accept and see it as it is. Seek professional help. You will be all right.

All the best!