I hate to be redundant but I still think you should check on amyloidosis. There are 4 types and they are not all the same. Just like cidp everybody is different.
It has now been 4 years since my husbands symptoms started but it took 3 neurologists and a misdiagnosis for my husband to agree to another opinion. He has the slow progressive neuropathy which goes along with his type of Amyloidosis.
You mention rituxan. I was under the impression that you could only get that if you had cancer also. Maybe it is different in England though.
One year ago my husband was playing golf now he cannot as his balance is so bad. If we go to any theaters or basketball games he either leaves early or waits until most people have exited as he would fall if too many people are around him. He is numb from the knees down and he walks with a cane. To bend down he has to hold onto something. Once he fell outside in the grass and had to crawl onto the driveway. I found him sitting there just waiting for me to help him get up. This falling and getting dizzy involves the autonomic symptoms but not for everyone. He is presently on a clinical trial in hopes of stabilizing. Please ask them to check for amyloidosis or keep treatments closer together. You just cannot do nothing.