My last menstrual cycle was on 20th nov, I had unprotected sex on 8th dec no ejaculation but took ipill. After 7 days I had some spotting brown discharge and my expected date is 20th dec and on 22nd dec I had heavy bleeding with painful cramps I bleed for 4 days day 1 heavy bleeding flowday 2 light bleeding normal flowday 3 mild spotting bleeding flowday 4 light bleeding normal flow those were my periods? Am I safe from pregnancy? Or it us implantation bleeding? After those 4 days of bleeding after 3 days of that why my lower back is paining. I am scared. Am I safe from pregnancy? Pls help me.