What exactly does plateau mean?

This is when, during treatment, you just stop improving. You don't really get worse, but you don't improve either. There are ups and downs in treatments, so it's best to keep a symptom journal so that you can see patterns, because some patterns can take weeks to complete and start up again.

mazerunner i use a scoring system for example any major symptom i want to track i have a column in a spreadsheet using N,L,M.S (None,Low,Medium,Severe). If you are having changes intra day you can do a column for say morning and another for afternoon/evening. You can also keep commentary in another column. this is invaluable as you go through the most likely inevitable weeks and months and modifying your regimen. sometimes you can't see the forest for the trees and this sure helps.