Low IgG in toddler

Hi all, so I took my toddler in (19 months) last Friday for reoccurring fevers. They did all sorts of tests on him. Today they called me back and said his IgG was extremely low at 345 and his IgA and IgM were kinda low. She referred us to an allergy clinic to get further testing to see if it could be a possible immune deficiency but they are scheduled for 6 months out. I’m looking to see if anybody else has had this with their littles and see what it could possibly be. Any help would be greatly appreciated.