bruise under toenail?

Hello~ I have a dark purple/blackish spot under my big toenail that takes up half of the toenail from the left side to the middle.
I didn’t stub my toe or drop anything on it so I don’t know if it’s a bruise, or fungus or anything!
It started when I went back to work as a waitress and I am on my feet all day. Both of my big toenails were sore, but now one of them has developed this “bruise”.
Do you think it is a bruise or something possibly more serious? I was reading something that suggested acral lentiginous melanoma a form of skin cancer so now I’m worried! Please help… Thanks!