That is the problem with Escargot - beautiful in summer, ugly and usually dead once you move it back inside for winter. Very susceptible to mildew in cooler weather too. Spray with a fungicide ASAP and remove infected leaves if you see mildew appearing or very blemished leaves. Find a place indoors that you can provide good light and lots of humidity - go easy on the watering indoors. I've got an Escargot inside one of the big clear pretzel containers you can buy now (Halloween) and rarely water it. I have another one outside but will be facing the same problems you have in a few short weeks.