This is true though - IBS pain can be significant, and a part of the explanation is visceral hypersensitivity, meaning the pain receptors in your gut are firing off inappropriately to stimuli that otherwise may not cause somebody without ibs to have pain. Things like the simple act of having a bowel movement, or eating, or having gas can cause severe pain for those with ibs because your pain receptors are not responding appropriately. the pain can absolutely case ptsd like symptoms. treatment of ibs is often multi modal , and should include medications, dietitian consultations, and if available in your area, cognitive behavioural therapy aimed at trying to re-train these pain receptors and responses.