Why has my finger gone numb?

As of around noon today, my middle finger on my left hand is numb. Just to the left of the nail, and only up around the nail.

No response to touch or pressure, no response to pain (although can get pain out of it deeper in, just not on the surface). It’s numb, not tingly.

I did spend about 4 hours dragging a rototiller around before this happened, and I’m curious if this had anything to do with it.

Any ideas, flutherers?