I have reason to believe that taking a course of medication (the antidepressant Effexor / Venlafaxine) triggered my CREST and maybe my Psoriasis. Naturally I stopped taking the medication once I suspected it might be a causal factor, and the symptoms have more or less stabilised but have not been reversed. I have filled out a Yellow card reporting this issue.
I would be interested to know whether anyone else has noticed a correlation between taking a powerful medication of some kind and the onset of Scleroderma. In my case it was about a two months lead-in time.