I have a hard painfull lump on my left leg very close to the shin bone. it hurts when i walk and also to the touch. it appeared suddenly.

See your Orthopod !: Sudden appearance of a painful & tender swelling in the leg could be due to a number of causes. It could be from a fall or stumble resulting in a fx or torn muscle; or due to an infection. All these would be associated with a history of a trauma or fever, etc. Rarer causes include a bone tumor breaking thru, resulting in sudden swelling, pain & tenderness. Bleeding vessel might also cause the same.