The last 2 times i've dyed my hair i've noticed a greasy type patch on the back on my hair a few days later and i have no idea how to get rid of it, i've shampoo'd it, conditioned it, shampoo without conditioner, conditioner without shampoo and it doesn't seem to go away. I know i rinsed all the hair colour out as its right at the back of my head bout half way down my hair (i have fairly long hair) and being in the shower to rinse, there'd be no way i could miss it.
Does anyone have any idea what it could be and how can i get rid of it?