Thanks for the query,
It might be a swollen lymph
Some times the lymph node remains swollen even after the infection subsides.
Dont worry it will not remain persistant.
Just keep a watch, if it increases in size, you must meet a doctor.
Please meet a dermatologist
for exact diagnosis.
Let me know if you have any other doubt.
you can ask a direct question to me on this forum, following the below link.
Wishing you a good health.