What colloidal silver products have you tried? The key with colloidal silver is to take enough of it. I suggest large amounts of either Utopia Silver or Mesosilver true colloidal silver plus Sutherlandia OPC, coconut oil and natural pathogen destroyers such as garlic, echinacea, oil of oregano and olive leaf extract.
As far as fasting, a one day a week fast where you take only your supplements and either water or juices/juiced vegetables and fruits would likely be a good idea.
I am not at all comfortable with a urine therapy fast for what you have described - though possibly others here who are more knowledgeable and experienced with urine therapy may disagree and have other input to give.