Hi Welcome to HEALTHCARE MAGIC..
I have gone through your query and can understand your concern...
No brownish pink discharge only once should not be a cause for concern. Sometimes a woman can have little bleeding or spotting in between periods.
If you had
unprotected intercourse 7-10 days earlier this could be
implantation bleeding. Implantation bleeding occurs after implantation(getting pregnant) in some woman & it occurs about a week earlier than your expected period. Bleeding is lighter in quantity & lasts for 3-4 days only.If you had unprotected intercousre then you should go for a
pregnancy test to rule-out possibility of implantation bleeding.
It could also be start of your menstruation(and this bleeding would get heavy) as you always had history of irregular periods
However repeated brownish discharge which is not your menstruation should be checked & treated for cause. Causes of repetitive spotting or bleeding include infection of pelvic organs, uterine fibroids,
cervix problems, polyps, etc
Refer to a gynaecologist, if problem persists
Hope this information helps