most likely what is happening is that your body is detoxing. one of the ways your body rids itself of harmful acids is thru the urine. so as you detox your urine becomes acidic, and this may be why your are experiencing irritation down there.
as far as minerals go i think the very best source is kelp. its inexpensive too. the "frontier" brand is definitely the best tasting brand, the "now" brand tastes terrible in my opinion. just taking a tablespoon or more of kelp a day with some fresh squeezed lemon juice will do wonders for your health and will help to nuetralize the irritating acids in your urine.