I was masturbateing and i lump formed in the shaft of my penis. should i be concerned?

Doctor can examine: One's primary care doctor can examine the penis if a new lump does not go away in a few days. Gentle masturbation should not create any new lumps anywhere. If excessive force is used, one possible cause of a new lump is the breaking of a small blood vessel under the skin, leading to bleeding and swelling at that area of trauma. As always in life, everything in moderation.