Here is a description of what IBS is, according to the NHS website. There is also a useful video which you may like to watch.
Irritable bowel syndrome (IBS) - NHS (www.nhs.uk)
Irritable bowel syndrome (IBS) is a common condition that affects the digestive system.
It causes symptoms like stomach cramps, bloating, diarrhoea and constipation. These tend to come and go over time, and can last for days, weeks or months at a time.
It's usually a lifelong problem. It can be very frustrating to live with and can have a big impact on your everyday life.
There's no cure, but diet changes and medicines can often help control the symptoms.
The exact cause is unknown – it's been linked to things like food passing through your gut too quickly or too slowly, oversensitive nerves in your gut, stress and a family history of IBS.

Britain leads the world in the treatment of IBS through hypnotherapy and yet this seems more like a well-kept secret rather than cause for celebration. Research has found that hypnotherapy may help improve the primary symptoms of IBS. It may also help relieve other symptoms suffered by many people with IBS such as nausea, fatigue, backache, and urinary problems. Hypnotherapy appears to offer symptomatic, psychological, and physiological benefit. Hypnotherapy may get to any emotional triggers and mosttherapists will work with clients to reduce any stress that may make the IBS worse. By using positive suggestion, hypnotherapy could lessen anxiety and increase confidence and wellbeing; this is believed to reduce sensitivity in the gut. Research has been undertaken by the National Council for Hypnotherapy and the results have been very positive for the treatment of IBS through Hypnotherapy.