A Large Lump Painfull Behind My Ear? What Is It?

This lump behind your ear can be swollen lymph node. Lymph nodes are small swellings which contain lymph and are part of lymphatic system. Their function is to fight against infection. These lymph nodes are present in different areas of the body and can swell as a result of infection.
Another possibility of this lump is simply a pimple. These pimples are usually inflamed and cause pain.
Another reason of this lump or swelling can be lymphoma or metastatic cancer. So, I advise yo to visit a doctor for proper diagnosis and treatment.

The lymph nodes are lower under the jaw bone in the neck blow the ear so that's probably not it... Any way it sounds like a cyst and I get them, but usually when I am wearing cheaply made jewelry. You should consider seeing a doctor about it.