Stopping drinking may be something for you to think about.

Having bilateral foot drop, suggests a spinal problem or
a compression of the peroneal nerve from behind the knees.

Surfing involves injuries at times and you may have hit the backs of your legs and compressed that nerve, which runs behind the knee.

Other injuries also can do this. People who skydive can compress this nerve when landing and injure it. Also sitting crosslegged for long periods, or kneeling etc.
This diagram shows the back of the leg where the peroneal nerve is located (yellow). It is quite vulnerable there and some lifestyles or sports can injure it.
http://www.google.com/imgres?imgurl=...QEwBw&dur=4862

So it is difficult to say what your problem is. But if I were you I'd stop drinking entirely and see if you improve and stay at a better functioning level. That would be your answer I think.

More on peroneal nerve problems:
http://www.nlm.nih.gov/medlineplus/e...cle/000791.htm