Before deciding this is solely or partially a soft water problem, it would be helpful to also review the ingredients in anything you've been placing in your hair recently. Does anything contain silicones ("cones")? Are you using thing with oil? Are there any ingredients common to all or most of the things you've been using, that your hair might be rejecting, like glycerin? Do they contain a lot of protein?
Also: Have you been applying a lot of thermal heat? Have you dyed or bleached it recently? Used henna or any other Ayurvedic herbs?
Most importantly: do you shampoo or not? When was the last time you used a clarifying or chelating shampoo? I ask that because many times people who call themselves CG take pride in never using shampoo, and they end up with nasty buildup. (Lorraine Massey's advice does NOT help everyone.)
Before doing anything else, I'd go ahead and use a chelating shampoo, following that up with a quality conditioner. That should remove at least some of the buildup, if there is some. Following that up with a PT sounds could, provided you aren't suffering already from protein buildup. (You might have to repeat the chelating poo if there's a lot of buildup)
If it turns out you really are suffering strictly from soft water, you may need to cut back on co-washing and just go back to traditional shampoos. The rationale for that is the shampoo may prevent what sounds like a possible over-conditioning effect the soft water is causing.