Hi,

Within the last few months I have noticed something unusual. When I have an erection I can feel a large swelling above my testicle, as if my 'epididymis' has swollen up (this could be a vein that is swelling with blood?). I'm really unsure what this is? Is it a lump or some kind of cyst? 

When not erect it feels fairly normal I'd say. Does anyone have any idea what this could be?