You have noted that this is associated with prolonged wearing of a cap or a head gear.This may be a form of contact dermatitis. I suggest that you have this checked by a dermatologist. Topical steroids are mainstay of therapy for dermatitis as well as antihistamines are also used for the itchiness. In your case, one has to ascertain the definite cause of this as these medications may have unwanted side effects.
Thank you for responeding to my question.
The dark patch is not itchy.
After couple few months of using bio oil, it seems to fade the marks slightly
I do not have any allergies that I am aware of.