It may be an insult to the blood vessel (or rupture). Blood vessels do not "break".
This is common in the fingers or toes. The body will naturally absorb the blood in the tissue (it will clot quickly unless you suffer from a clotting problem or are on meds).
The above picture is certainly an infection (the skin was opened). There may or may not be a ruptured vessel. You can dig into the skin if you like, but you should probably just treat it with some antibiotics.
I am almost sure that there is no subungual melanoma that frequents the nevi in the nail beds and could present difficulty in reference to the differentiation from the subungual hemationa and a chronic parconychail infection.
If the problem does not quickly improve in just a few days, you need to see a IM doc.