Go to the hospital - it could be a lot of things! See the URL below.
http://www.wrongdiagnosis.com/sym/dark_skin.htm
symptoms.
* Bruise
* Purple skin
* Blue skin
* Mole
* Malignant melanoma
* Seborrheic wart - also senile wart
* Freckles
* Cafe-au-lait spots
* Hyperpigmentation - and various causes of hyperpigmentation including:
o Sunburn
o Stopping the pill
o Radiation therapy
o Adrenal disorder
o Addison’s disease
o Liver disorder
o Intestinal disorder
o Malnutrition
o Vitamin deficiency
o See also causes of hyperpigmentation
* Pregnancy - causes the “mask of pregnancy” (a darkening of cheeks and forehead); also darkening nipples, genitals, and a line down the central abdomen.
* Chloasma - brown pigmentation on the face in pregnancy.
* Sun sensitivity - from various possible causes.
* Hemochromatosis - can cause a brown or “bronze” skin color
* Varicose veins - may cause ankle skin darkening.
* Venous ulceration - from long-term varicose veins
* Familial polyposis - causes darkening of skin of the gums.
* Acanthosis nigricans
* Erythema ab igne - red-brown discoloration from heat exposure.
* Dry gangrene (type of Gangrene)
* Mongolian blue spot - a blue/black spot on the buttocks or lower back region.
[See full list of 55 causes of Dark skin]
Please accept my thanks for your trouble in taking the time to post this list.