Hi,
Welcome to the ehealthforum. I am glad to help you out. This kind of bump can be a swollen lymph node, a sebaceous cyst or a lipoma. Lymphadenopathy (swollen lymph nodes) is usually caused by a viral or bacterial infection. Other causes include allergic reactions, arthritis, cancer, metabolic diseases, and an overactive thyroid (hyperthyroidism).
I suggest you to get this lump examined from a physician and get a fine needle aspiration cytology done to confirm the diagnosis. 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.