My daughter has severe IBS and no inflammatory bowel disease and yes gumby, she actually suffers a lot more than what you've described...she is often on the toilet crying in pain for 2 hours or more, at a time.
Some believe that it's not possible for an IBDer to also suffer with IBS and some of us that do, know better lol....
From the CCFC;
"You may have heard of irritable bowel syndrome (IBS) and wondered if it is the same as IBD. While often confused because their names are similar and their symptoms can seem comparable, the two are not the same.
Yes, both diseases affect the digestive tract. However, with inflammatory bowel disease, inflammation is the key characteristic. In irritable bowel syndrome it is thought that problems arise because of changes to bowel function or the way the brain senses what is going on in the bowel; inflammation does not play a role. It is possible to have IBS if you have been diagnosed with IBD. It is also possible to have just one or the other."