Are there any warning signs an ibd flare up is coming?

Many times! Most patients with ibd have a "intuitive" sense of when the flair is coming up!
Multiple signs. Warning signs are increase abdominal pain, diarrhea , urgency, rectal bleeding and increase mucous in stool, weight loss, fever, increase fatigue.Rectal pain, pelvic pain .Laboratory exam could show anemia which is low red blood cells count, high white blood cells count, elevated sed rate and CRP which are signs of inflammation.