Missed pill ?

So I usually get my period 1st day of every month. I just recently had it. I'm currently about two weeks left until my next cycle, but I accidentally forgot to take my birth control pill for the past 3 days. I had been feeling cramps all evening, but about an hour after I took the pills I started to get a heavy blood flow. I'm still new to the world of birth control pills. So I'm not sure if this is normal? Will it go away Or do I have to wait it out as a normal period? Is it even a normal period?