1gunrunner--
You have Onychomycosis. Nail Fungus--it originates as Tinea Pedis (athletes foot), the skin fungus starts in the damp area between your toes, goes out through the tip of your toenail and works its way back through the nail until it reaches the matrix (the "root" of the nail under the skin).
Topical stuff might work--
If you have insurance, they may (they consider it a cosmetic problem) pay for Penlac nail laquer. It is a clear nail polish that you put on the nail once a day, and take it off once a week with Rubbing alcohol or nail polish remover. The topical stuff might work if you start NOW--once it gets back into the matrix, it needs to be killed with internal medicines.
Lamisil or Sporanox are the oral medications of choice. Generally, you get one months supply, and you get your blood drawn before you start the medication, and before each refill (they are checking for liver function markers). There is a slight chance of liver damage (low incidence of it <1:1000), and if you are on other medications, you probably don't want to take it. These are also fairly expensive, require 4 months (depending on your doctor and the drug, it can be pulse dosed, given 3 months on, 3 months off, and again for another month, etc.).
If you don't have insurance, something called "Fungoid Tincture" does work fairly well in some cases. It is supposed to be Over The Counter.
In any case, if you wait much longer, you will have to go with the Oral meds. If you start now, you will still have a good chance to catch it with the topical stuff.
Come see me in about 4 years when that hammertoe starts to bother you a little more--bring a couple of preban rifles (Machine Guns are nice too!!) and we can work out a swap--I'll fix the toe(s) for you. [:D]