Hello So About A Month Ago, Out Of No Where,

Hello so about a month ago, out of no where, I noticed a bump about the size of a pea on the upper portion of my shaft of the penis below the head. There is a lump under the skin that is hard and it grows and shrinks constantly. If I put my finger on it it feels much like a small rock and its movable. When I squeeze it between fingers it feels Veiny. When I am erect it is noticeable and larger as well often times. Its been almost a month since I noticed it and still hasnt gone away. Its also skin colored, no redness and not painful. also it is not poppable I have tried. Please help!