Painless Lump On Mastoid Bone

Approximately 3 months ago I was suffering with what seemed to be a chest infection. My gp said it was probably viral and therefore did not prescribe antibiotics. The illness continued and I returned to my gp about a month later. He prescribed me a course of amoxycillin and I felt much better. Around about the same time I noticed a small lump in what seemed to be the lymph nodes behind the ear. Knowing that i'd had an infection I was unconcerned. A few months on the lump is still there but it doesn't feel like a lymph node anymore. It is solid, painless and I am not able to move it. There is no associated ear pain and my blood tests (esr and total count) were normal.
I returned to my gp who on examination said that she was convinced it was bone but she referred me to ent to rule out whether it is lymph or not. I'm still on the waiting list to see a consultant.
I have started to get a strange slighlty numb/tingling sensation on two areas of my head. I'm not sure if the source of this is my scalp or my bone.
I was wondering if anyone could shed some light on this. I'm worried it could be somethng more sinister than a swollen lymph node.