Hi, I took Emergency Contraceptive pill once, it was about 3 months ago. I had un protected sex for about 10 minutes until he later put on a condom. So I am sure there will be some ejectualtion of pre-. So do I need to take the EC pill this evening? Because it is most effective in 72 hours. I need some advice. And can taking EC pills harm the fertility and any part of my body?

It is most effective the sooner it is taken, it has almost no effect after 72 hours.

Yes, it is effective for the one sex act it is taken for. So yes you need another. They are not for normal birth control, so you can not take too many of them. If you are sexually active why are you not on regular birth control

Also remember none of them are 100 percent effective