The Marshall Protocol was developed originally for people with sarcoidosis, for which it did maybe have some success.
The trouble is with it, apart from the avoidance of vitamin D is the very low, subclinical amount of antibiotics that are prescribed.
I suggest that you peruse the antibiotics forum here and also dig out a few of the antibiotics threads from the regimens forum. You may also care to look at this site:
where you can contact someone called Reenie, who used to be a moderator on the Marshall site until she jumped ship and realised what she was doing to herself. You can also write to Katman either here or there, but she is having computer trouble at the moment. She started CAP antibiotics for her PPMS and has made amazing progress, recently seen climbing a long ladder to repair their barn roof.
Finally you could do worse than peruse my husband's website:
. As a medical microbiologist he knows more about this than most people.