Thanks for the query.
Yes, usually brown colored blood indicates accumulated blood in the endometrium.
According to your history, there is possibility of some hormonal
As you took over dose of medicines, that might have altered your hormonal levels, leading to continuous spotting.
So you once consult gynecologist, get examined.
With her suggestion, go for ultrasound
By these, the possible cause for your problem can be identified.
If there is hormonal abnormality, taking the hormonal pills for few months may regularize your cycles.
If thyroid abnormality is detected, you have to use concerned medicines.