Thanks for writing to HCM.
Your last periods were almost 20 days back hence implantation
can happen if egg has been fertilized.Though there was no ejaculation fertilization can happen as prostatic secretions and other secretions produced during intercourse can contain stored sperms.
Hence get a pregnancy
(UPT) test done.
Implantation bleeding happens when the egg implants into the uterine wall.This event usually happens between 6 and 12 days after conception. If you experience bleeding before you are expecting your period, it is likely implantation bleeding, but if the bleeding is close to the time of your expected period, it is likely a regular period.
Implantation bleeding varies in appearance, but typical reports of implantation bleeding tell of a small amount of pinkish or brownish blood in vaginal discharge
The main difference between a regular period and implantation bleeding is that the discharge is not similar to a regular period in color, amount, or duration. Implantation bleeding will be scant in amount and not last very long.
Visit to a Obstetrician for confirmation and pregnancy testing.
Hope this will help you.
Wish you good health.