ITP and CVID - Need Help!

My son is 17 and this is his 3rd diagnosis with ITP. In 2013 he responded well to IVIG and steroids. In 2015 it took a little longer but he again responded well to IVIG and steroids. His most recent diagnosis was Sept 2017. His #'s are often in the single digits. He is not responding to IVIG or steroids so we started Promacta (eltrombopag) 50mg. He went up to 46 but then declined to a platelet count of 5 in 1 week. We changed him to the max does of 75mg and his platelets spiked to 96, then 87, then 46 and now 7 as of yesterday. These #'s are just over 1 week so he declines rapidly. So, it appears he's not responding to Promacta which has a 95% success rate. During the past 6 months the physicians have done tons of testing. His IG levels are extremely low so they are thinking he as CVID (commom variable immunodeficiancy). We have one lab to get back but they are thinking of starting weekly home infusions of IVIG for his IG levels. Although IVIG did not work for his ITP they are confident it will work for CVID. I'm wondering if anyone out there has CVID and ITP and if so, once your IG levels increased, did ITP go away. He is 17 and is an avid soccer player and skier. Needless to say, with platelets in the single digits, he cannot do anything. He's had bouts of spontaneous bleeding this time which has never happened in past ITP episodes. It seems as if this round of ITP is much worse than it has ever been and he's just not responding. Also, did anyone else try Promacta? Did you increase and fall again? Did it eventually work? I'm stressed and sad that I have a child I cannot fix. Any and all suggestions welcome. He did have a bone marrow biopsy upon initial diagnosis in 2013 and that seemed fine.

you may want to copy & paste this in the adult with itp section under the newly diagnosed or general itp discussion.

Thank You