Yep. 10 mins B4 a bleed began I would get 'the runs' even if a period wasn't due. Then it would start.
In my earlier menstruating years I would feel incredibly nauseous which returned in my later years: 10-14 days B4 a period.
So yes bowels can be affected by hormonal upheaval.
How long B4 you get your cystoscopy, there should be a 2 week pathway. If U haven't heard by Monday give the GP a ring and check that the appt has actually been sent! U should B able to check at the dept how soon you are likely to be seen.
Let us know how you get on.