It is, unfortunately, not possible for me to make a specific diagnosis based upon such a general description of this skin lesion, as I cannot examine you. However, you may have an inflamed or infected epidermal inclusion cyst (sebaceous cyst). These cysts often present on the back of the neck, and typically have a dark black spot near the center (where the blocked oil gland opening is located).
When inflamed, these cysts may need to be treated with antibiotics or/and surgery.
Sincerely/ Robert A. Wascher, MD, FACS
www.doctorwascher.com
www.oncoguard.com