Fibre is important, flaring or not...when flaring you can always stick to unsoluble fibre and/or cut your fibre down a little to possible help the flare out some but my GI told me to start taking fibre supplements when I was at my very worst...and of course it added discomfort (excess bloating and gas) but this is normal and to be expected with fibre until your system adjusts to it (that's why most avoid it, cuz they ccan't bring themseles to adjust to the discomfort of the added bloating and gas) once your system has adjusted then it's amazing all the benefit from it...he told me to take it daily and indefinitely...I can now eat all fibreous foods without getting all gassy/bloated...my bloating is completely gone, I have very little gas, stools are formed, no mucous, less frequency.
You don't have to dive right into fruits, veggies or grains, you can build your system up with supplementation. Even though I eat fruits, veggies and seeds on a daily basis, I still take my fibre supplement daily.
It's important to drink plenty of water with your fibre supplements and on a regular basis anyways, cuz like fibre, water is also very important for bowel function...fibre also helps sweep the bowels of bacteria. It also aids with D or C.
:)