gum boil with swollen cheek in 9 yr old

My daughter woke up with a swollen cheek on right side, she's had a gum boil there for a few days and I'd been cleaning it with hydrogen peroxide and it was going away but now her face is swollen and the entire top section of her gums on that side is swollen as well. She had tooth work there over a year ago, had a root canal. Is this an infection from this root canal and will the tooth need to be extracted, it's still a baby tooth? Will antibiotics help and how dangerous is this infection?

[Jerome Tsang, DDS]

If its an abscess it can be very dangerous.  She should get the tooth treated (most likely an extraction is my guess).  Antibiotics should be taken as well due to the infection spreading beyond the tooth and into the cheek/gum area.