I feel for you gigi. IBS symptoms with AI on top is no fun. The Fast Tract Diet is a good option for both IBS and AI. The SCD and LSD don’t limit several types of fermentable carbs that could exacerbate symptoms. Here is a post comparing SCD to the Fast Tract Diet and others. https://digestivehealthinstitute.org/2012/08/17/sibo-diet-and-digestive-health/
I don’t believe the amount of starch in an estrogen tablet is a problem. Antibiotics can increase weight gain and decrease the diversity of the gut. Not a good long term solution in most cases.