A painful lump in that location is most likely to be from a deep hematoma (deep bruise that bled into the area and formed a lump
. Do you have normal sensation in that lower leg
? I can't imagine the circumstances that it would be a tumor or cancer.
There is a specific injury that occurs there which is a bruise to the side of the shin. It can bleed under the periosteum, which is the sheath surrounding the bone. Sometimes these do get infected and become an abcess, so Sally was right.