Blood since time of year..?
Answers: Hi, it could be any of the things you mentioned. If you have particularly rough foreplay or intercourse it could be bleeding from a small slash or abrasion. It sounds like this may be what it is. But if that's the valise it should go away today.
Spotting is usually muted red blood, it's more brown (though it could be red). So, if it's more brown it's probably spotting and not an injury.
It could also be a light term. Of course, just because you never have spotting or a light length doesn't mean it can't come about. Women's cycle's change adjectives of the time, unless you're on birth control to regulate it.
I wouldn't worry too much unless the bleeding continues within an irregular way (not consistent next to your period or an injury). Then you may only want to talk to your ob/gyn.