Bleeding after masturbating?

Usually when I'm off my period, or sometimes when I'm on (over the pad of course), I masturbate at least twice a day, and after these sessions I often bleed overnight, even when I'm long off my cycle. I didn't know that this might not be normal until I joined this app and saw nobody else talking or complaining about it, so I need some advice. Is bleeding after masturbating normal, or should I be worried? Just to keep in mind, I've never used toys or fingered myself in my life—it doesn't do anything for me—and the blood is usually a bright red, unless I just finished my period. Thank you!