Easily irritated, cry over little things

Hi I have been feeling really low since past few months or year.I cry a lot over little things.Even if my PC hangs a bit ,i get this irritating feeling and start crying.I shout at the peak of my voice.I even get chest pains sometimes after yelling..And once i stop, i feel like nothing happened.It was like someone else got into me.there has been lot going in my family..My sister is staying away from her husband with us since two years...even the name of that person -her husband makes me angry and lead to bursts of crying.I am totally negative on further aspects of life because of their marriage output. And note that i am very humorous too at times...i have very jolly nature..m not shy,m an extrovert.People look upto me to have a good laugh.But actually one moment i am crying other moment m laughing with evryone...i dnt understand...any little to little trigger cn make me furious and lead to crying.