the OP said...
For me the key sign of a flare is blood - otherwise I have no real urgency, pains, malaise etc... i.e. my life goes on almost normally, except for the bright red blood I get on the paper
If you have formed stools with the only other symptom being a little blood then you may not be flaring at all, perhaps you just have some hemorrhoids. I would check that out before escalating to something more drastic.
about
15 percent of IBDers are helped by antibiotics, and apparently you and I are in that group. Flagyl knocked out my flares more than once. I really do not not not want to depend on abx for remission because they do have side effects and I am afraid that someday they will stop working, and that would send me up the creek. So I try to stay in remission by keeping a food diary and taking supplements, antibiotics are only a last resort.
If you are taking antibiotics then you should also take probiotics along with them. ABX kill both good and bad bacteria and you will need to replace the good bacteria. For example Flagyl has been known to later cause C Diff infections. A good probiotic to take while on antibiotics is S. Boulardii which is a probiotic YEAST and therefore immune from being killed by the Flagyl. And it specifically targets C. Diff. I take an assortment of probiotics and it seems to help.