Tips for helping my 3 year old son's nasal pages?

he has really large, hard boogers and wanted to know how i can loosen or soften. i was thinking about purchasing and warming up saline/salinex nasal spray, would that work. would a humidifer also help during the nite. the past few nites he has been coughing and throwing up phlem. i do have a doctor's appointment tomorrow as well.