he certainly needs a doctors treatment, if not rehab for drinking 20+ years.
My brother died of liver failure, so I do know the signs... what I can't understand is, you say his liver was ok, but the signs you are describing sound like he is not. Does he have any fluid retention in his stomach, are the white of his eyes yellowing? If so he needs help fast,. Either way I think you need to get him to a doctor. How much is he drinking?
You need to get him to the hospital. You cannot do this alone. He needs nurishment and fluids first and foremost.
I am sorry this is happening but I don't think anyone here can help you with this nor should they try. It's medical and you should take it very seriously.