Welcome in H.C.M.
I have gone through your query regarding small lump behind your left ear for last 6 months.
As you said this lump is there for last 6 months and un changed the day you have noticed it . There are mainly lymphadenitis
, sebaceous cyst
are the common lumps of this particular area.
You are advice for FNAC from lump to confirm the pathological nature of lesion and accordingly that may be treated.