implantation 4dpo?

Hello! Is it possible that an implantation takes place on the 4dpo? Today is my 4th day, and I was having incredible pain, so I thought if it is happening today!!!

Yes, it is very possible. Implantation may take place anytime from the 3rd till 7th day post ovulation.

I had sex with my husband four days ago- now I have some very light brownish bleeding, and mild cramping. My cycle is regular, and I never spot between periods We had unprotected sex, but he did not ejaculate inside of me. From everything I've read, implantation bleeding doesn't occur til 6-10 days after fertilization. As I mentioned, it has only been four days since we had sex, but it was when I was ovulating. I am not due for my period until another nine days. Could this be implantation bleeding?