The best one by far is www.theguttrust.org They have a free helpline staffed by specialist nurses to give advice and support and can put you in touch with a self help group if you have one in your area. Professor Peter Whorwell a Gastroenterologist at Wythenshaw Hospital, Manchester has had some marvellous results with Hypnotherapy so if you live near that may be worth a try.I tried a high fibre diet and it made me worse and have now cut out wheat and dairy products and also take probiotics and after many years as a sufferer I'm feeling so much better.