I think the tips & Stalls section have many hints and ideas of the NO-NO foods for you. Also go back to the Atkins book and re-read it, it also has all the foods listed that could cause problems. Another thing you mentioned was that you are drinking Low Fat hot chocolate mix??? Low fat does not mean sugar free, just as sugar free on the hot chocolate mixes generally still has carbs. So, you may want to read the label on that mix, it could be a culprit also. And drink plenty of water, your deep purple may mean dehydration not ketosis.

Hope this is of some help.

Good luck
Cindy