Nail fungus occurs when a particular type of fungus becomes uncontrollable and spreads to the nails. When that happens, you feel some pain, and your nails will become dark and thicker. Worse yet, it emits an unpleasant odor that can be contagious in case you are not keen. Yes, this illness is terrible as it can spread to other people if you don’t seek the right treatment right away. Different nail fungus treatments Many people with this condition have many treatment options available.