From what I understand about alopecia, it is considered to be an autoimmune disease where the immune system is actually attacking the hair folicles. It also seems to be aggravated by stress. I have never worked with it personally, but, in my research, it appears that people have had success using cedarwood, lavender, thyme, and rosemary oils directly on the scalp. If you have seen where colloidal silver was successful, I wouldn't hesitate to use it topically - I would not use it orally.
Again, I would take a serious look at diet - why is the immune system over-active? There are several herbal formulas which help to calm the immune system, so this is something I would also consider using orally.