Excessive Flatulence?

This New Year's I've resolved to drop a few pounds. However, since I have begun my diet I have had a lot of excess flatulence, accompanied by constipation, and hemorrhoids. I've been eating healthy foods, taking vitamin and mineral supplements, drinking tons of water, and I have avoided many fats, complex carbohydrates, and sugars. I know that a failure to break down carbohydrates can cause gas, as well as an increase in dietary fiber. But, I am not eating anything unusual, and certainly nothing that I have not eaten in the past. My gastrointestinal issues are becoming uncomfortable, embarring, and even painful at times? Does anyone have any suggestions?