Looking at your photo it could be a sebaceous cyst. But to confirm this please visit a dermatologist! ASAP. Most of the times, the only treatment for a growth is EXCISION. It sounds scary maybe but it should be relatively simple procedure. The details of the procedure can only be discussed once the lump is diagnosed. So, go to an allopathic dermatologist and get yourself diagnosed. ,Do not delay.

Nothing much helps. U can apply a paste of dashanga lepa mixed with water twice daily. Medicines available at Ayurveda stores.