Are you using any clarifying treatments every once in a while? You may need to if not, but thats just a guess, that perhaps your hair needs a break from the conditioning and co-washing. Just a guess. Do you do anything differently on that side when you style, co-wash (like which side you part on, do you massage scrub harder on one side because your dominant hand moves more comfortably on that side -- I've noticed I do that sometimes). Do you sleep on that side? Have you started to pineapple your hair when you sleep or wear ponytails a lot? Any of these could cause friction, or strain on your hair leading to breakage. It may or may not be related to the CG method.