Sugar alcohols can cause major intestinal problems if you eat too many. Furthermore they are often used in "frankenfoods"...those products whose ingredients you can't pronounce. If you're not sure what most of the ingredients are, you probably don't want to be eating it!
You are allowed 75 calories each day from non-nutritive sweets. All sugar free candy falls into this category. The main reason we are limited is to keep us from going through what you did, rebel! If you keep to 75 cals, you won't have those side effects. On the other hand, some of us have found that we still suffer when we eat sugar alcohols, so you may want to try a small piece of something and make sure that it doesn't bother you before eating 75 cals worth.
In addition, part of the reason for doing SBD is to make a change in your eating habits...to eat more healthy food and less processed food. If we keep eating the same things we always ate, but in SF versions, we aren't likely to make as many healthy decisions. So try to keep these in moderation. Once you get to Phase II, you'll be able to have real chocolate once a week. Why not wait for that rather than eating the SF stuff?