Hello Thorcat and thanks for posting, 

I'm afraid I can't tell you exactly what the odds are, but positive FIT test results certainly aren't always due to cancer, I think more often they aren't. You probably already know that a positive FIT test means blood has been found, but that is all - the reason for the bleeding has to be investigated. Several other conditions can cause bleeding and your change in bowel habit might not be related to the bleeding or both could be due to something else. 

Although bowel cancer is a possibility after a positive FIT test, more people will be diagnosed with another condition that explains the bleeding. I don't think you can find out much else at the moment.  I appreciate that having to wait to find out what is going on might be unsettling.  If you can, try to dwell on it and wait for the next steps along the way to getting an answer.  

Give us a ring if you want to talk anything over, our number is Freephone 0808 800 4040 and we are around weekdays, 9-5.

Best wishes,

Julia