Firstly, lumps in the male breast are common in the pubertal age of 13 to 19 years. This is called Gynecomastia. But they do not have a white head, which is suggestive of a Sebaceous cyst which you have burst. Did some secretions come when you popped it. Secondly, on popping it, the cyst cavity becomes susceptible to secondary bacterial infection which might be the case with you now specially if there is redness and pain in that area. You should take a course of antibiotics like Tab Augmentin 625mg thrice a day along with Tab Ibuprofen 400mg twice a day for five days and put warm compresses over the area and you will feel better. Let me know if you dont feel relieved. Take care. Dr Rishi.