How can I get rid of an hungus inside one of my feet toenail?

I dont know why is this happening, I dont have athletes foot, Im always taking care of my feet, so they can look perfect.How can I get rid of an hungus inside one of my feet toenail?
I saw my doctor years ago about this and was asking about the medication you see on TV about it. He said he'd prescribe it if I was really sure about it but that he normally trys to sway people away from that to topical solutions instead because of side effects. If I remember right, the pill for it can be really rough on your liver and the effectivness on the toe fungus is so-so at best. His suggestion was to file the area down a little each day and apply an anti-fungal cream on it then to leave it out when not wearing shoes. For wearing shoes to have some clean breathable socks on.How can I get rid of an hungus inside one of my feet toenail?
see a dermatology or it could be discolor .