brown toenail fungus picturespurple discoloration under big toenailtoenail discoloration yellowtoenail fungus discolorationdiabetes toenails discolorationhome remedies for brown toenailstoenail discoloration whitetoenail discoloration blackthick discolored toenaildark discolored toenailtoenail pain and discolorationbrown toenail discoloration treatment