If your kidneys are in bad shape they may not be able to get rid of toxins loosened by MMS. Congestion? It may be a sign of you need to go very slow with very little for some time.
A general detox rule is one's kidneys must be able to handle the garbage on it's way out.
DMSO would regenerate any damaged or inflamed kidney tissue, not do damage.
Also, your pain sounds like kidney stone symptoms. That would be about as bad as you describe. In case you may need to get "stone-breaker".
Badly congested kidneys would be serious enough. But I wouldn't worry about any lasting damage. Go slow.
Disclaimer:These statements have not been evaluated by the Food and Drug Administration. MMS (Master Mineral Solution) has not been FDA approved to diagnose, cure, mitigate, treat, or prevent any disease. Chlorine Dioxide is also called MMS throughout this website. License: Except where otherwise noted, content on this site is licensed under a Creative Commons Attribution-NonCommercial-NoDerivs 3.0 Unported License.