Hi, I Fingered Myself Last Night And After I Reached

Hi, I fingered myself last night and after I reached orgasm, I realized I had blood all over my hand. It was fresh blood. I decided to check it again this morning, I put a finger it and saw the blood has turned brownish. It doesn't flow out or something but it is still there when I dab my vagina with a wet tissue. And my period is in 13 days. So did I just injure myself without realizing it? Because I might be a bit rough with myself when I was masturbating last night. And should I be concern about this? And will it heal it by itself? This is the first time this happened to me. Thank you.