What Causes Dry And Liquid Discharges After Periods?

hi doctor
why do i get a brown discharge after my period? i know we do still get dry blood discharge after our period but mine is really liquid type of discharge even after i had the dry blood after my period. it feels like i am still on my period but it is dark brown discharge and while i am sleeping i feel the discharge and i have to wake up and clean my self and even when i am just sitting i feel the discharge on my underwear and now i have to keep wearing a pad.
so pls help me
i have seen a doctor for it and they took a culture for test and said there was nothing wrong