Share 'A few questions wrapped into one post....'

I have a condition on my arms, I forgot what it was called but my sister and I have had it since birth and the derm gave me ammonium lactate for it. Are there any alternatives to that? Also, any natural alternatives to sunscreen? This doesn't have to do with skin, but I can't help but put on some crest white strips every couple of months (in moderation) and I was wondering if there was somet...