My Daughter Is 19 And Away At College. She Has

My daughter is 19 and away at college. She has a lump on her neck (beneath her ear) that is painful. She said she noticed the pain about 10 days ago. She thought she slept on it wrong and just had a still neck. Now she has a lump there and she said she can feel something in her throat when she talks. She went to Health & Wellness at her school and they tested her for mono. Both finger prick and blood work came back negative, although her white bloodcell count was slightly elevated. They gave her a antibiotic and said if anything changes she should go to the ER. Her throat is not sore but she has discomfort in the back of her throat and the lump is still there. Any ideas what this could be?