2 Months late, AF came yesterday

Jessica 😻
I hadn't had my period since 5th of July until Yesterday. 
I didn't have spotting I just started to bleed very heavy midday, Today I am having the worst pains in my lower tummy, thighs, lower back I have ever had.
I'm changing my Tampon nearly every 30mins because it's that heavy. 
I am irregular due to PCOS but I haven't been that irregular before or have I had very heavy periods. 
Is this normal?? 
Might it be because I missed one ??