I am really glad you wrote.
Our moods and emotions (things like anger, happiness, sadness) are all controlled by chemicals in our brain. When we have any sort of prolonged stressor, our brains over produce some of these chemicals. So they don't just sit there, the brain aborbs them again (it's a release -aborb cycle), but with stress, the brain over produces and absorbs too quickly -- not allowing us to use them properly. That process causes us to have mood swings, feel and express anger, get depressed and overall feel rotten.
To fix it, you need to take medication that regulates that process.
What *exactly* you have will be determined by a Psychiatrist (don't see your regualr MD, go to a Psychiatrist). This could be Depression or it could be Bipolar - but the Psychiatrist will ask you question to determine exactly what you have and give you a prescription for medication that will stop all of this.
How else can I help?