Rashes are normal part of fasting and detox. I have one so many fasts and I always had rashes, I must as sometimes less sometimes more, sometimes lumps in many areas, etc.
For me it always starts after day three or four and stays even after refeeding starts.
Creams are not helpful and also may have chemicals in it that your skin absorbs. The best thing works for me is coconut oil. I apply oil everytime I feel the oil is evaporated from my skin.
Another remedy I have used is Apple Cider Vinegar.
Keep up the good work, this rash issue shall pass.