Hi. I have IBD and, just recently, started to get anxiety as well. I can relate to what you are saying. You are not a baby at all. When I am sick, I am constantly worried about
where the closest toilet is, if the sound i am making going to the toilet will be heard by others, the smell of it will be smelt by others. There are many things that are the consequences of IBS and IBD and unfortunately they aren't nice consequences. And yes, we all feel little aches, paints etc but many people don't have health issues either so they most likely don't think twice. The part about
how you get pain and start worrying it is cancer, that is all related to your anxiety. Anxiety can make something a lot bigger then what it actually is and our brains start to go into overdrive thinking of these possible negative scenarios.
I hope this helps.