Hello, So Im Supposed To Get My Period The 21st

hello, so Im supposed to get my period the 21st and I am very consistent, I had regular PMS symptoms the week before the 21st such as cramping, moodyness, clear discharge etc, but I masturbated a day before my expected date (the 20th) and after that I started getting very painful cramps, and now I am about 3 days late into my period and I am worried about what is going on.