I can understand your sufferings from mutiple problems. The red mark can be simple pigmentation or may be a sign of systemic illness which needs proper evaluation and diagnosis without which it may cause future problems. For the red marks to you can apply cortisone
cream and take benadryl
by mouth. You should tell your doctor regarding the red marks as it may be a sign of some internal problem. This do not appear to be related to any nerve irritation
as nerve irritation do not manifest as red marks or related things.