Bipolar will anyone talk to me about it

Hi, I have a son that is believed to be bipolar. He has been addicted to drugs in his life ,an alcoholic , lost his wife , children, license. He has quit everything at the time being. Needs to be on meds. And won't take them...I don't understand how he feels. I see how he goes from happy and calm to raging . Can anyone explain it to me.