Good evening. How can I help a child with phlegm? I'm doing massage, d…

Good evening. How can I help a child with phlegm? I'm doing massage, drinking plenty of fluids, the air temperature in the house is 22-23 degrees Celsius, humidity is 40-50%. But the mucus has been sitting for two weeks. She doesn't want to do inhalations anywhere. She chases her around here and there. And how long does it take to go away?