What Causes Red Bumps On Bottom Of Feet?

My sister is 38 and has red bumps on the bottom of her feet, they look likearge blistees, they r sticky and smell. There are three of them one of which is slightly between the toe. She said their painful too, with a slight itching.
She does drink a lot of vodka per night at least a half bottle and she mixes with coke, also apprrox 15-20 ciggs a day.