oxycarbazepine induced hypogammglobulinemia

My son has had partial complex epilepsy since we has 4...that is 5 years. We had always been well controlled on Lamictal but last December just grew out of a very large dose. We switched him slowly to Trileptal. About a month after switching he bagan having one infection after another. Before this year, this kid has been on antibiotics twice in his life: NOW...first we had a positive strep throat culture treated with Cef. Then his feeding tube site (we also have Systemic Mastocytosis) got yeast treated with nystatin topically but that didn't clear it we we took Fluconazole. Then a mino cut on his leg developed cellulitis that was treated with Augmentin. Then the full blown flu, in April despite him getting a flu shot! After the flu his G tube site was junky again and treated with 10 days of PO Clindamycin. Then strep throat one more time....except at that visit I made the doctor culture the tube site which was now had pus again. We started Keflex for the strep throat and the tube culture came back positive for Pseudomonas A and Klebsiella O: so we added PO cipro on top of the Keflex we were taking. The tube site stayed infected and developed an upper respiratory infection..... He was admitted to the hospital for 10 days of IV Zosyn: they re-cultured the g tube site and the Peudomonas was still growing but now had Strep A. We were discharged from the hospital with a PICC line to finish the 10 days of Zosyn. He needed another 10 days of Zosyn started within a week and then had a viral GI bug with a crazy high fever. Through all that, his epilepsy was stable as can be on Trileptal.... The doctors finally drew immunoglobulin levels on Zachary and him IgM and the B and T cells were almost absent. Pretty much as vulnerable as the Bubble Boy! A quick search found two other documented cases of Trileptal bombing out immune system. We have begun to wean the Trileptal. My questions are: How quick has anyone come off of Trileptal?? Zach's seizures are partial-complex but we still don't want him to have one. Has anyone has a sharp increase in serious infections on this drug?? Are we really the third only case ever??