Dark Discharge

Hi ladies, I have a question and I really hope some has the answer. (Going to be a little TMI) The other day I had a little fun with myself, if you know what I mean. Today when I woke up my vagina was burning and throughout the day i experienced a dark discharge. Almost brownish like dried blood. I experience a burning sensation in my vagina before and after my period so I thought maybe that was a sign until I saw the discharge as well. Does anyone else experience this? Was my masturbation the cause?

Thank you for any help!