How do i deal with my anger when even doctors can't tell me whats creating such a drive?

I am a 16 year old boy and i have been mad almost everyday for a year now. it isnt any type of frustration type anger or even a common anger. as stupid as this sounds the only way i can describe my anger is like there is an animal in me and its not even me. i have done the whole anger management bullshit but it doesnt work for me. ive literally tried everything. im not looking for a way to handle it anymore, i just want to understand what it is that im feeling. when im mad im incredibly strong compaired to how i am usually. if im in a fight my friends have to literally pull me off of who ever the kid is im fighting and when they do they always tell me i have no color in my eyes, like the black part of my eye took up the entire visible part. im not scared of whatever it is that is happening to me. i just need to figure out what the hell it is.