My nails are showing black color in its proximal part.what should i do?

Fingernails? toenail: Unlikely you've hammered all of them. See doc 2 b checked for infection &/or compromised circulation. R u diabetic? Sugar control essential 2 prevent fungal infxns of (toe)nails, but vascular problems may b part of problem (in older pts). If only toenails, make sure shoes fit properly so toes aren't jamming against end of shoe. May be normal in afro-americans. See fp/podiatrist 2 decide.

Many possibilities.: Some causes of nail discoloration include trauma due to tight shoes, infection, and medication side effects. You should try wearing shoes with a higher wider toe box. Get the feet inspected by a professional to determine the cause of the problem, as treatment varies depending on the diagnosis.