No need for him to 'out' his problem. I'm assuming he has good insurance and all people need to know is that he had to take care of some medical issues. Nobody likes to pry deeper when you phrase it that way and it's nobody's business but his and yours.
The doc is a friend - maybe go see him sooner than later? It got so crazy around here while my beloved was trying to sober up that I literally hid drinks in creative places around the house and let her know where one was every two hours so I could go to work. ....that is crazy... WTF was I thinking?
Hang in there, sounds like you love him dearly and while that won't cure an alcoholic it sure doesn't hurt ;-)