Not preg, have a tiny brown/black spot on bottom of left nipple, you know how the nip is divided into parts? 1 part is discolored brown cancer or mole

Monitor it for chang: Pigmented lesions on the skin, if they are brown or black can be a mole, some of which are dysplastic requiring careful monitoring and ? Excision, if they become suspicious for melanoma. I would advise you to learn about warning signs for a melanoma which are described with the acronym: abcd. Please know, irregular lesions if bigger than 4-5 mm require a biopsy if they change size/color.

Hard to tell : It is hard to answer your question without an examination. It is concerning when moles change - change in size, color, become irregularly shaped, itch, bleed. Most moles are relatively easy to remove and test. Please see your primary doctor or a surgeon to see if this needs to be removed and tested.