Aslm. I am always confused as to when to make ghusl and start fasting. My period ends on a Sunday (5 days), on the Monday I might get some brown discharge. I do not know whether I should start praying and fasting on the Monday and disregard the discharge or of the discharge is still considered part of hayd which then makes my total period 6 days.
In the name of Allah, the Inspirer of truth
Any coloured discharge/spotting, other than clear or white, seen in the possible days of menstruation (hayd) is hayd as long as it meets the minimum threshold of 72 hours (3 days and nights) and does not exceed the maximum of 240 hours (10 days and nights). Hayd must also be preceded and followed by a minimum 15-day purity.
From the information you have provided, the brown spotting will be part of your hayd, provided it meets all the conditions outlined above.
And Allah knows best.