Vaginal bleeding. Of masturbation?

My friend is having vaginal bleeding. It started first when she was masturbating, then she bled for the first time, after that 2-3 times on the same day, then it stopped the next day, then she again bled after 1-2 days again. It's been 3 weeks when it stared, and the bleeding hasn't stopped since, she's not bleeding continuously but like once in two-three days since then. And also she did masturbate in between this time. Also, she is very irregular on her periods, though she gets her period around month end or starting, firstly she did confuse it with periods but she bleed very irrularly, like one day she's bleeding heavily, the other day no sign of it. What could possibly the reason? Why is she bleeding like this? Is this because of masturbation?