8 months postpartum and i just now am getting brown spots under eyes and above upper lip. is this a late mask of pregnancy or vitamin deficincy? fix?

Melasma...: This could be melasma which is increased pigmentation of the skin in areas exposed to the sun. To avoid getting worse use high SPF(protective) sunscreen lotion. There are a few creams that can be used, like for example hydroquinone, for treatment but needs to be prescribed. I would suggest you to see a Dermatologist(skin doctor) for final diagnosis and treatment.