My best friends GP told her she had IBS. It was cancer. Again discovered when she took herself to A&E.
I am 20 year survivor of advanced bowel cancer who was fobbed off by every GP partner (bar one) in a large practice over the course of a year. At the time, appointments were easier to come by and I had at least 10, all with an actual GP, before being offered a referral for "health anxiety". My notes make me sound like some kind of Victorian "bluestocking" and contain more references to my marital status and my father's suicide than to my actual symptoms. No tests were ordered and the diagnosis dismissively offered by one GP (like the PP above) was IBS.
I now pop up on threads like this to remind people not to accept IBS as a diagnosis from a GP without further investigation, such as a colonoscopy. IBS is a diagnosis of exclusion, not of "fuck knows and I can't be arsed to look properly". Unless you are willing to let the NHS play fast and loose with your health, all unexplained symptoms of bowel cancer (change in bowel habit, abdominal pain, bleeding, etc) should be investigated, especially if there is a family history, and you are NOT too young. (I was barely 30 with no family history).
Most people with these symptoms will not have bowel cancer, and I appreciate that GP's have to make difficult decisions about referrals when they may see multiple people with abdominal complaints that turn out to be self-limiting. However, that's a "them" problem and is presumably the reason why they are paid so handsomely.
Since then, I have recovered from cancer, sued the NHS for negligence and married a physician. One of those things, not sure which, seems to have stopped the standard GP routine of delays and fobbing off and I have received nothing but excellent service from my current GP practice.