I have tingling and numbness in my arms, fingers and toes for months now. I also have a hard painful lump behind my left ear. What could this be and wha?

Numbness. Numbness and tingling feeling usually an indicator of nerve irritation which could be from several causes from vitamin deficiency to cancer. Lump behind the ear again from different tissues, lymph gland, cysts, tumors. It really needs exam and some labs if warranted.