Good Ways to Keep Calm?

It's been brought to my attention that due to a preexisting neuro condition I am prone to cerebral edema (brain swelling) specifically on the right side of my brain when my emotions get too high. If I am extremely mad, excited,sad etc the right side of my brain reacts to the excess pressure on my brain and swells. (This has already happened 3 times to me) Anyone have some really good ways for keeping calm that worked? I've tried meditation, going for walks, and tea with no luck.