I have never encountered this problem, but perhaps because of the advice I would give ? ;)...
1. skin brushing -- are you doing this daily? if not do it!
2. Liver Flush
-- have you done this? if not do it! get instructions on this site, it's gross but incredible effective.
also, perhaps it's a reaction from your body's now-increased sensitivity, to something you're using/putting on your skin? soap, perfume etc?
all kinds of interesting 'stuff' can come up during your first fast, if you eat healthily after your fast is over, you'll never be 'so toxic' again.
i did mc for 12 days 2 years ago, for serious degestive problems I had for over a year...and since I have been very healthy, generally speaking! i am going to (try to) do it again starting this Friday, you'll see more of me soon!
also, I would highly recommend, for general skin/body health, that you commence the following:
1. eat (at least) 2 tbsp per day of flax oil
2. stop eating fried foods/cooking with oil (if you do)
if you eat oil, only eat uncooked! like olive oil on salad, avocado etc. i have found these 2 steps have greatly improved my skin health, and permanently stopped my ecxema.
good luck, yours in health -- gary