Brown period

Hi! Just looking to see if anyone has similar experience and can offer advise other than “go see a doctor”.

My period has never been regular, my whole life up to now, I am now 29 years old. However the last 4-5ish months have been pretty regular. (Not on birth control and truly don’t want to be on medication) this month (august) my period was “22 days late” according to the app. Well I finally got the period and ruled out pregnancy. My period has been a dark brown in color. Light flow, nothing heavy. How long does brown blood last? I know that brown blood symbolizes old blood but I’m wondering if anyone has any knowledge or experience with this situation?