Some people are particularly sensitive to changes in the binders used in pill manufacture by different brands. The active ingredient is the same but the binders (the substances that hold the pill together) differ. A clear difference is when a binder may not be suitable to someone who is lactose intolerant, but some people find more subtle differences give some unpleasant results. So definitely not gaga, if you can get back to your usual brand and the symptoms vanish, you may have your answer. Best wishes.