I am undiagnosed at the moment due to having no health insurance or finances for testing, but I have all the symptoms of Crohn's. Since my early teens (I am 25 now) I have had periodic flares of mouth sores- anywhere from 3-10mm in size, white in the center and red around the area. They are one of the most painful things I have experienced, especially when eating acidic foods. Since my gut symptoms have started to get worse in the last 5 years or so I noticed that the mouth sores always show up when I have a flare up. They are also brought on by stress- recently I started a new job (a stressful experience as I also experience generalized anxiety related to working) and sure enough, within the first few days of work I had a new sore pop up on my inner lip. My gums swell sometimes too, I have found that I cannot floss as this makes them swell and bleed every time. I use a waterpik instead. Orajel if your friend for the sores!