Suggest Remedy To Prevent Skin Darkening Due To Cold

Hi,I am from India but presently in US.AGe 25,female.I came in december.from then on my skin is becoming darker and darker.i met a dermatologist here but he says its due to cold and they is no way out.my skin is very much sensitive so i dont use any cream except fair& lovely cream nor any facials also.I am very much worried abt this.Please guide me in this.

thank u.