Hello Sugarplum 89, and welcome to our little corner of the forums.
I agree with Brenda here... Has your dad been seeing a doctor? There's a "chance" it could be something else. I'd like to be able to give you a more definitive answer, but a lot of alcoholics seem to be able to hang on, up and down, for a long time. I know it can be very difficult for a daughter to see this happening to her father.