I Have A Mass On My Neck; Just Had Biopsy

i have a mass on my neck; just had biopsy with report reading polymorphous lymphoid population present; I understand that means clear of cancer however what actually causes the lump to begin with (been slowly getting bigger for 2 years; tender to touch; causes fullness to ear); my dr is sending me to an infection control dr to find out reason; he declined to give any medication due to the mass causing fullness in ear and discomfort with turning head/sleeping; what is your take