Hypogammaglobulinemia: Caring for my teenage son

Hi everyone. My 15 year old son was diagnosed with Hypogammaglobulinemia almost 2 years ago. He has had horrible stomach issues along with this finding. He has had a lot of testing done with Gastrointestinal and Immunology the last two years. But nothing else has came about or looked into more. We have not had any help in him managing this. He has had to hole school due to the everyday fatigue, stomach issues, bone and joint pain. I wish someone was pull look into bone issues but no one will. He continues to get cold/ flu like symptoms every couple weeks. He also has sleep apnea and he sees an allergist. He continues to have high lymph count on all his testing and has had high T and B cell counts. Does anyone have pointers for us or suggestions? I feel like throwing in the towel sometimes because no Dr is open to more testing or looking further. I’ve advocated for almost 3 years for him and the weight on this moms shoulder is getting so heavy.