I have a small lump (knot) behind my left ear, It s been there for about 2 or 3 years now and is now causing problems so as blurred vision out of left eye only, really bad headaches, ringing out of the left ear, trouble hearing out of left ear. I had a normal Ct scan and a Ct w/ contrast done. The Dr. told me that they believe it might be in my lymphoid. What might this lump be