only if you have money to waste.

There is a correlation between this and some sort of medical problem, I remember hearing about them when I was taking care of my dad after his heart surgery. GO SEE A DOCTOR!

Yup. When in doubt, it's best to see a doctor. Better safe than sorry.

That usually means trama to your nail, It's nothing to run to the doctor about, you might of injured them, and don't even remember doing it. Those lines should grow out along with your nail growth, if you don't see a change in months from now than go to the doctor, but you don't need to loose sleep over this.

Lines going up and down? I will assume this means from the base (Where the nail goes under the skin of the toe) to the tip (the part you clip). Injuries, like dropping something will cause black and blue from side to side usually, in some rare instances, depending on the shape of your nail and whether you grow ridges or not, you will get a line up and down. However there would be tenderness if not pain at the location, meaning it is a bruise and you would feel it. Further there would be other colors to go along, depending on how old the injury this can be purple, blue, red, to yellows. You would have remembered injuring your toe, so I think it is safe to rule out a simple bruise. Black is usually dried blood, hence bleeding/clotting disorder. Sometimes it's B12/Iron deficiency. Splinter hemorrhages can be a sign of heart problems, but generally are a different thing all together. They are mostly caused by tiny voids in the nail plate cell production. They fill up with blood from the nail bed and appear as tiny black lines that look much like you have a splinter under your nail. Your nail plate will ride forward on the nail bed much like a train rides forward on its tracks. The rails are on the nail bed, and the grooves are on the underside of the nail plate. The voids are usually on the underside of the nail plate which allows them to fill with blood from the nail bed. They usually are nothing to worry about unless there is a history of heart problems in your family. If so, then I would have a stress test performed if your doctor believes it to be warranted. OR possibly it is Melanonychia where there are vertical pigmented bands, often described as nail 'moles', which usually form in the nail matrix. Seek a physicians care should you suddenly see this change in the nail plate. It could signify a malignant melanoma or lesion. Dark streaks may be a normal occurrence in dark-skinned individuals, and are fairly common. In any case you will want to keep and eye on these, if you get more or these appear to grow or thicken, then it is best to see a physician to find out what is causing them exactly.