HI Katejo, I think it probably is likely it was the delay in patch change. Ive found any gaps can be a trigger for me too. I think some people must be more sensitive to hormonal fluctuations than others, which produces bleeding. Just a theory. Ive had a week with no bleeding and feeling good but woke this morning with a pounding headache and stomach cramps and had spotting again. Feeling rubbish and bleeding seem to go together for me so I'm guessing its hormonal rather than a physical problem. Let me know how you get on with your appt, good luck with that and I hope the cystitis settles, its trully horrible.