I noticed these pin head sized black dots under my skin on one side of my buttocks. What could it possibly be? It's not raised at all and don't feel like bumps of any sort either
You have comedones.
comedo is a clogged hair follicle (pore) in the skin. Keratin (skin debris) combines with oil to block the follicle. A comedo can be open (blackhead) or closed by skin (whitehead), and occur with or without acne. The word comedo comes from Latin to suggest the worm-like look of a blackhead that has been secreted. The plural of comedo is comedones.
The chronic inflammatory condition that usually includes both comedones and inflamed papules and pustules (pimples) is called acne. Infection causes inflammation and the development of pus. Whether or not a skin condition classifies as acne depends on the amount of comedones and infection. Comedones is plural of comedo.