Hi Rocky robin!
That's a good question! At first, it feels as if I just have a few bad days in a row, maybe eaten something I can't tolerate that well. Everything feels a bit sore, feeling nauseous, don't want to eat much, feeling fatigue, a bit like having a minor flu or something. Pain in my lower right abdomen gets more intense, frequency of bowel movements might go up but not necessarily, feeling bloated very often, gastritis pain coming back, arthritis getting worse (but not necessarily at the same time, can take a few days), mental wellbeing getting worse as well. Normally, I feel really crappy being in a flare-up. I can't concentrate on anything, I'm not very sociable and can't even tell why.
My first flare took about 9 months because my Crohn's could not be diagnosed earlier, my current flare-up started getting really bad in May. No idea how long it's going to take until I'm finally in remission. But, I have to admit, even though I'm still in a flare-up, it's not getting worse and worse mentally over time because now I am very open to everyone concerning my disease, so that makes it a lot easier having a flare-up but still taking part in some social activities for example and not feeling as isolated as I felt during the summer.
When did your flare-up start? Are you having a flare-up at the moment?