Diagnosis is made based on clinical exam and can be confirmed by viewing scrapings of the nail under a microscope, or growing the fungus in a culture medium. This is not an easy condition to cure, so rather than trying home treatment with over-the-counter medications, it's best to see your doctor. As with many conditions, nail fungus infections are easier to treat if you catch them early.
Food intolerances — Some yeast infections are due to food allergies. Try to avoid foods that cause negative reactions of any kind and pay attention to symptoms you experience when eating things like dairy, eggs, certain nuts, wheat-containing foods and grains. If you think you have a food allergy or sensitivity, try an elimination diet to figure out what foods are causing intolerance and work on removing those foods.
Use soap and water to wash your feet, and dry well, including between toes. Trim your toenails -- straight across -- to keep them shorter than the end of your toe. Make sure the tools you use are clean, too. Wash clippers and files with soap and water, then wipe with rubbing alcohol. You might be tempted to cover up discolored nails with polish, but don't. Your nail bed can't "breathe," which keeps fungus from going away.