Thank you for your query.
You mention that your daughter has flu
like symptoms and her cheeks and neck are swollen. You also ensured that she had her flu shot during this period. I hope she has been seen by a doctor and is on some medication for her illness. In case no doctor has been consulted then she should be examined by a doctor who shall get appropriate investigations done and start medication.
I hope I have answered your query to your satisfaction.
Wishing your daughter an early recovery.