Kinda going through the same think right now with my dad. My grandfather was a wicked drunk, used to beat my grandma, ended up most always sobering up in jail after his benders. My father for as long as I can remember drank beer, never really got carried away. In the last ten or so years since us boys moved out he has got out of control, to the point of non stop tremors,drink the hangover off (yes even at 6 in the morning) And more recently has become addicted to small bottles of fireball whiskey,which is really doing him in. He was actually able to completely quit drinking from june 13th until a couple weeks ago. It started again with a beer or two and progressed back to the whiskey. Now he is full blown back being drunk again. I don't know why but he tries to hide the whiskey from my mother, she finds half drinken bottles everywhere "stashed away". When he is sober his is the most happy, loving, lets get things done type of guy. When he's drunk he becomes short fused,loud,obnoxious,rambles on,makes false plans,and simply gets nothing done. My brother, mother and I ,are trying to decide what to do next. It's hard us living in a different town as well,we don't see the half of it.
All I can recommend is read,read,read up on addiction, seek councilling or a professional in the field, and there are online forums you can sign up with , for some help from other people that may have had to deal with a similar situation. Good Luck