Oh Dear
I am so sorry that this is still going on. This was quite commom in the '80's and early '90's when there was litigation regarding Myodil. People were re-diagnosed with MS and when the litigation ended were then re-rediagnosed. It was a very distressing time for them. It is to do with the demyelanation and I know DocSarah has written up about it. Will go off and find a link on the website for you. The treatments appear to be the same for both conditions (apart from Interferon).
Will try by tomorrow
Bye for now
Kim