Fungal infection of the nail, or onychomycosis, is an infection underneath the surface of the nail caused by fungi. Nail fungus may be ugly and embarrassing. The nail often becomes darker in color and foul smelling. Debris may collect beneath the nail plate and it may start to deteriorate.. White, yellow or brown spots may also appear. These infections need to be treated to prevent additional problems such as ingrown nails, bacterial infections and other problems. Treatment may consist of Laser, topical or oral meds. Laser treatment of fungus toenails is the safest with the highest success rate