All of this is nonsense. Colloidal silver supplements are also heavily advertised as powerful antimicrobials and immune system stimulants, capable of curing up to 650 different diseases. Again, none of these claims have been proven. At one time, silver products were useful as germicidals, but they've been replaced gradually by more effective ones. And no matter what the promoters of colloidal silver tell you, the human body doesn't need silver.
Safety is an issue, too.
If taken orally, it can accumulate in the body's tissues and cause a disfiguring skin condition called argyria . Skin pigmentation, especially around the nose and mouth, turns bluish, permanently. Those affected have been described as looking like corpses suddenly come to life. Medical literature also contains reports of neurological problems that developed in long-term users of oral silver products. My advice is to stick with the antibiotic treatment your son is receiving.