I have slight discoloration on my big toe on my left foot. i've tried over-the-counter ointments which haven't worked.?

Maybe fungus: You would want to cut as much of the discolored nail away as possible without cutting the nail too short that it would hurt. Topicals are not the most effective, however, if you cut enough nail away, a topical may work if it is only a small area you are dealing with. I would try that before orals or laser.

Get checked: I would start by having your family doctor check it out.

Possible fungus: If the discoloration is on or under your toenail, than it can be a fungus. If it is a black area, it may be a bruise under the toenail. You will need some type of antifungal treatment. If it is the toe itself that is discolored, depending on the color it could be a bruise, dermatitis or fungus, or possible blood clot to the toe. See your podiatrist for a more detailed answer and examination.