Hello,
There is no medical condition as such which causes oiliness of the hair.I would suggest you to clean your hair frequently with a mild shampoo(you can use the ones for oily hair) and don’t apply any conditioner on the hair.Also you can shampoo twice during each wash and apply shampoo on the scalp without piling the hair on top.
Hope it helps.Take care and pls do keep me posted on how you are doing or if you have any additional doubts.