There are herbal treatments for IBS as Heather has on this site. However the oil of oregano product doesn't have any information about how it may affect the digestive system. It specifically says on the site "This product is not intended to diagnose, treat, cure or prevent any disease" and also "may provide support to the immune system". This does not look like a product for IBS or any digestive problems.
It's ok to try new products to see if they help you, we are all different. But we're trying to give you the best advice that we know, and we're advising against using this product for treating IBS.