Not sure what’s happening

Hi, I’ve had CIDP for about ten years now IviG had been working pretty well for me 75mg of Privigen fortnightly, but now it’s only last 8 out of the 14 days. My right side of the brain wants to go to sleep and having memory issues to, I’m now back to shuffling when I walk but still have the sensation of my legs collapsing from under me. Finding this very frustrating. Any ideas could be helpful. I’m in Australia.