It could be a sebaceous cyst.
Hello,
Scrotal masses can be caused by several conditions; the most common are a Varicocele, which is a varicose vein along the spermatic cord; Hydrocele, wherein a fluid collection is present in the scrotum; Spermatocele, a cyst-like mass within the scrotum that contains fluid and dead sperm cells; Hernia; Infection like Epididymitis; or Tumors. Hydroceles, varicocele, and spermatoceles are noncancerous and usually do not require treatment. A lump caused by an infection is treated with antibiotics. I would recommend that you follow up with your Doctor so you can be examined and an ultrasound can be done.
It is very difficult to precisely confirm a diagnosis without examination and investigations and the answer is based on the medical information provided. For exact diagnosis, you are requested to consult your doctor. I sincerely hope that helps. Take care and please do keep me posted on how you are doing.