Hello and welcome to the forum.Regarding your question about flare,well that's a difficult one.As you'll appreciate,as symptoms,diagnosis and treatment are different for everyone,then so are flares.
To generalise, continuous pain,mucus,blood,fever,nausea are all symptoms of a flare.Either just one symptom or all of them at the same time.You should recognise when things have gone to far and it's time to visit ER / or outpatients dept.Only you know your own body and whether or not you feel bad enough to seek help.If that's the case,then DO NOT HESITATE. We are all here to help and advise where we can,so please feel free to ask.
Also,try not to worry about it.Some of the forum have been in a flare for months or more,others only have them occasionally,and some are in remission for months or years.As I said,we're all different.