as a nail tech i have to say....
make sure your toenails are filed down properly. because i run i have to keep them very short (in salons, state regulations prevent us from trimming them down to short for sanitary reasons) or my toes/toenails get sore. shape should be straight across and rounded at the edges to prevent ingrown toenails. it is also better to trim down your nails with a clipper first then file instead of filing them down to as short as you want them. a file is to shape not take off massive amounts of length.
its true that a former injury to the nail bed will cause an infection/fungus if it isn't healed properly. if the nail bed is damaged things like to grow underneath. specially if it is in a moist environment often. to help prevent it make sure you wash your feet with an antibacterial soap if you have problems often. tea tree oil is a good natural product to use. you can put it on your nails to help "sanitize" them and help get rid of infections.
a major problem is wrong fitting shoes. yes i know its hard to throw out those shoes that are oh so cute or so expensive that you bought and you still feel you have to wear them (i have been guilty of this also) but proper fit is important. not only for your performance but for your feet and nails. if a shoe is to small it has a tendency to put extra pressure on your nail beds and cause problems. either the nail bed will lift and bacteria will get under the nail or you can have the splits in your nail itself and the bacteria will get under as well.
foot and nail problems aren't fun at all, specially when we have to use them all the time. for fungus treatments, like lamisil or the nail polish one or any otc treatment, its one of those things you do have to wait out untill the nail completely grows out to see the complete result when the fungus is gone. its frustrating i know, everyone just wants it to go away NOW! just like a bruised nail, that you have to wait to grow out, it just takes time. just put nail polish over it and make sure you change your polish once in a while so you can keep an eye on how the fungus (or other damage) is doing while it grows out.
and don't make me tell you some of the horror stories that i have of toenails, everyone who didn't want to go to a salon, went to beauty school to get their nails done, and i mean EVERYONE. :eek: