Honestly if your worrying is getting out of hand like mine was go back to your doctors and explain you’re anxious - they should be able to reassure you as they’re the experts in all this. I’ve read and been told it’s very rare that anything could happen within those three years especially if your last test was normal -plus I haven’t heard of bowel changes being one of the major symptoms - I mean you’ve been told you have ibs so surely it’s that? I would go and see your doctor again - I hate that I wasted two weeks of my life panicking when I didn’t need to. X