It's not cancer. It is a small blood clot caused by stubbing your toe. You have to watch these closely because they can become infected and cause loss of a toe and osteomyelitis. The best way is to use a digital camera on close up to photograph it every day.next to a ruler. If you have diabetes you should watch your sugar and don't hesitate to go to a podiatrist.
A couple weeks ago I rolled a heavy chair over my toe by accident though I didn't notice the dot until now.
Did you stub your toe lately? I had this same concern last year. I stubbed my toe and the toenail was dis colored. It was def my toenail because as my toenail grew, the discoloration of the nail grew as well. Evenly, my toenail grew out along with the discoloration. Does your toenail bleach when you press on it? I don't believe melanoma will blanch.
Did you recently hit or drop something on your toe. Could just be small blood blister underneath