Coklat gelap tu biasa je, especially towards the end of your cycle, darah lama yang keluar last, so colour dia lebih pekat macam tu. A few of my mum friends and I were just discussing this last week actually, and we all agreed it's totally normal! But kalau it happens every month and ada cramping yang heavy or bau yang strong, better check with your doctor just to be safe, especially if ada perubahan lain ke kat cycle you.