Gluten is often cited as a cause of IBS with constipation, and it may be worth trying a gluten-free diet. As for your iron-deficiency, if the pills are causing more harm than good- you should try looking for more holistic alternatives in the exhaustive list of herbal supplements such as Jobelyn Blood Builder. A nutritionist can help draw up an Elimination Diet where you cut out foods one by one and gradually reintroduce them to see when your symptoms recur. Your sleep pattern would be restored soon as your bowels settle down. Good luck and God Bless.