I cannot imagine how frustrating and scary this must be to you. Has he not ever been offered IVIG? I have CVID with 2 subclass deficiencies. I've not heard of having high B & T cells. in the face of low IgG. I know in my case, I have impairment of those cells to come to my defense. Usually with low globulins you'll see people getting upper respiratory or sinus infections. Personally, I get a lot of infections related to staph and fungus and oddly, also present atypically. But many do have gastro symptoms like diarrhea, myself included. I also get small bowel bacterial overgrowth that feels like I swallowed a ton of air and that upsets my stomach and gut. When I have that, I can instantly vomit with no nausea as a warning. What did the gastro workup find? Are you seeing an immunologist associated with research or at a teaching university? Honestly if you have been dealing with this for 2-3 years with no answers, let alone treatment, I highly suggest you go to Mayo. Or at minimum, a medical university. Once you've been to Mayo, at least short-term, you have access to follow-up. My own immunologist speaks worldwide at conferences and publishes medical articles, but I got really lucky finding him. I'm also wondering if there could be something else going on that isn't directly related to low IgG. Like a autoimmune disorder or conditions that use a lot of IgG. This is another reason to go to Mayo as they have a full range of specialists under one roof. What could take years to figure out, Mayo can get done in a week or two. With respect to high lymphocytes, I just want to clarify that T-cells and B-cells fall under the category of lymphocytes. So when you have a over production of T & B cells, I can see why the general umbrella of lymphocytes would be raised. I honestly wish you and your son will start to see some answers. It doesn't sound like that is going to happen with the doctors you've been seeing. Here's a couple articles worth reading: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6787951/. https://www.sciencedirect.com/science/article/pii/S009167492200152X