What Could Cause A Solid Lump Above My Right Incisor, Noticeable From Inside My Right Nostril, With Mild Throbbing Radiating To My Forehead?

Hi Doctor, I have become acutely aware of a lump, which is fairly solid, above the incisor on the right hand side of my mouth. I cannot actually say with any certainty how long it has been there, but I became hyper aware of it a day or so ago while touching my face. It is not painful, but i can feel a mild throbbing, which radiates up to my forehead. This lump can be felt from inside the right nostril. In comparison, on the opposite side of my mouth, above the incisor on the right, the area is indented and hollow. A finger tip easily rests in the space. Any assistance is much appreciated. Thank you