Hi You may be having a frictional hyperpigmentation. This is darkening of the skin due to frequent rubbing especially if you are sweating a lot. Avoid harsh face washes and use a ph balanced glycolic acid face wash twice a day. Pat your face dry. Avoid putting fairness creams as some of them could worsen your condition. Use a broad spectrum sun screen regularly to prevent further pigmentation. Use a good moisturiser lotion. Eat foods rich in omega fatty acids such as fish or almonds as well as foods containing lycopene and bio flavonoids which are natural skin lightening agents. Tomatoes and spinach contains the above. Please contact a dermatologist who can examine you and prescribe the appropriate skin care products and treatments as chemical peels laser or dermabrasion.