I was on my period for 5 days and my flow had stopped to where it was not much at all so I had sex on the 5th day. Ever since I had sex I've had bright red blood and it's been the heaviest flow I've ever had for 2 days straight. Is this normal? Because my period should be over by now but it's still very strong. I'm 18 and I've had sex 3 times before this.