I had unprotected sex and i'd done a test to confirm ovulating on 14th oct, on 20th oct started with brown discharge it's now dark red today, implant?

Possible: Implantation bleeding is not really as common as the internet would have you believe. When it does happen it's usually 6-12 days after ovulation. A pregnancy test 7-10 days after unprotected intercourse is much more helpful. Implantation bleeding occurs exclusively in pregnant women.

When is your: period due? It might be the start of your period. Usually there isn't bleeding with implantation. When it does occur the amount is very tiny. Would take a home pregnancy test if you don't get a definitive period on time.