A hard bump on the back of the neck hurts commonly due to the following reasons: first, folliculitis, generally do not worry too much, you can apply topical drugs such as iodophor and Bactrim, you can also use iodine for disinfection, and then alcohol for deiodination, generally about a week’s time swelling and pain can gradually disappear. Second, sebaceous cyst infection, which is caused by the obstruction of hair follicles, need to go to the hospital to perform physical examination and neck ultrasound for clarification, if the disease, the swelling needs to be removed under anesthesia, if not treated for a long time may lead to further aggravation of the swelling and pain, and even local ulceration, pus flow, resulting in scar formation. Thirdly, pain caused by lymph node hyperplasia, which requires further blood tests for clarification, and if necessary, puncture biopsy of lymph nodes or excisional lymph node biopsy to clarify its nature. In conclusion, if there is persistent swelling pain, you need to go to the hospital in time to clarify the cause.