Flare up indicators

What symptoms do you get that warn you you are about to have a flare up?  I usually get an ulcer or two in my mouth which then multiply

Hi, Ididn't get any warnings, my gp thought it was thrush. Only by the 3rd skin byopsy the Consulant at Hosp found it was crohns of vulva.

Hi 

I start with not eating, that always a good indication, for me 

Hi, I think I have canker sore inside my bottom lip. Do you get them with flare up?

Not sure what cankers sores is, but I have just had some very large ulcers, about 8mm x 3mm, which coincided with a flare up, plus sore throat ( chocolate makes it feel like it's on fire!).  This is how it usually starts, plus lower back pain.  steroids from the doctor are sorting me out

Hi, There like ulcers.