Crohn’s disease is a chronic inflammation of the digestive tract, most commonly the ileum. It can be very painful and generally results in diarrhoea. It is a very rare disease affecting only 1 in 150 persons in the UK. It is most common in people between the ages of 16-30 and also European Caucasians. Symptoms are not always apparent. A patient can go for months trouble free. But these periods are often followed by very uncomfortable ‘flare ups’. It has similar symptoms to irritable bowel syndrome and ulcerative colitis, making it difficult to diagnose.
An NHS surgeon summarises Crohn's disease

This is an image showing severe Crohn's Colitis in the sigmoid colon from a colonoscopy.
Colonoscopy image courtesy of Wikipedia under creative commons license
Help?
Below are some links to other websites which offer help and information to people who suffer from Crohn's Disease.
https://www.bbc.co.uk/health/physical_health/conditions/crohns1.shtml#whats_the_treatment
https://www.nhs.uk/Conditions/Crohns-disease/Pages/Introduction.aspx
Did you know?
Crohn’s disease occurs much more commonly in ‘White’ Caucasians and Jewish people. Research has shown that Caucasians are four times more likely to develop the disease than any other ethnic group.