kidney side effects of cs?

I have had some interesting side effects here and there of taking Colloidal Silver . I get gripping in my kidneys and then my low back gets really tight and aching.

taking phosphoric acid diluted in water like I would for kidney stones seems to help in a few hours.

is this die off? something else?
I am getting benefits of cs but my brain is still paranoid that I am poisoning my kidneys.

any ideas or experience to share out there?