How do i get him to stop drinking and seek professional help?

.: First step is for the person to acknowledge there is a problem. Get family and friends or his doctor to talk to him. He has to get out of denial and seek medical support. It cannot be forced on anyone. It is better if the effort is voluntary. So let him realize his problem.

Family intervene: Try a family intervention and see if that helps. Hard problem to solve unless the person wants the help. Good luck.

Not in that order: Sometimes you have no choice but to seek help first, and then obtain sobriety. Remember withdrawal symptoms can be severe if someone stops drinking abruptly after drinking large amounts and or for some time. So you have tools like aa, al anon (for relatives or friends of drinkers), besides community mental health, detox and rehab centers available out there to help you. Good luck !

You can't!: Well, you can try, but you risk getting him upset, which may or may not be worse. I suspect you can't convince him to see his family doc. Best option i can think of is for you to get support from al-anon (http://www.Al-anon.Org/). And read http://www.Aa.Org/pdf/products/p-30_isthereanalcoinyourlife.Pdf for starters.

Well, I think: The only thing you can do is help yourself. Al-anon fellowships can give insight in your situation. Getting someone who is potentially an alcoholic to stop drinking is almost impossible unless they are willing to quit. Good luck.