hello and welcome to hcm forum,
i would like to inform you that your daughter has been suffering from the tooth problem for quite a while now and it has become chronic, and as you said the swelling has become hard, i would recommend its better to visit an oral surgeon as the tooth might go for extraction.
swelling is getting bigger because , infection has spread to the sorrounding tissue, therefore do not delay the appointment with dentist
Also ,do not apply warm compresses over the area,
ask your daughter to use an antibacterial mouth rinse(3-4times/day).
i wish her good health.