Good Evening. Upon Arriving Home This Evening I Noticed That

Good evening. Upon arriving home this evening I noticed that my 7 year old son had a nodule located on the left side of his jaw line. He denies pain. The nodule is movable and firm. Three months ago he was diagnosed with strep throat. He had no pain with a strep throat. The only symptom that we know this was his breath we took him to the dentist with no problems there and then we went to the doctor where he tested positive for strep. He was given a round of antibiotics that he finished. Now I have noticed the lump on his jawline this evening. He does not currently have a cold or running fever.I am at a loss and unsure of what to think. Please help. Thank you so much.