There are a few things you can start of with:
– Make use of those things that are calming for you
– Try and refrain from staying in places or conditions that make you angry
– Salawat
– Move from those circumstances when you feel the anger coming
– Wudhu
If it is unintentional due to your health condition as you said then don't press over the issue that it is a sin because that will make your mental health situation worse. Do istighfar for the mistake but don't keep on pressing on the matter of it being a sin.
Such thoughts will worsen the situation. Continuously try and calm yourself and ask Allah for help.