How long have they been like this?? Did you some how damage the nail?? I have had this happen at times when my nail was bent at the tip.
Is the nail lifted?? Are there any funky odors coming from your nails?? Is it coming from the edge of the nail or the center?? Fungus usually starts at the edge or tip of the nail unless you somehow damaged or cracked the middle of your nail.
If I were you, I would keep track of it for a couple weeks before doing anything with it. If it grows out with your nail, I wouldnt worry about it. But, if the band keeps getting wider and/or changes color then it is time to act. You can either see your doctor and he will take care of you, or you can buy an over the counter product like FungiNail.
Good luck, nail fungus can be tricky to get rid of.
Christine