Stay strong bagpuss, think how far you've come.
Try and rationalise the craving for what it is, just a craving. If you drink what benefit is alcohol going to give you? It will just numb the craving till tomorrow and make you feel awful. Whereas if you fight it, you're one step closer to being stronger and more able to fight these off.
You're doing brilliantly, 4 days is a massive achievement. Focus on that.