I don't know if it's cold sores or ulcers, or both. Maybe it's neither. But I get these sores in my gums that are very sore,and they come when I'm at my worse. Is this a viral infection that flares during fibro? Is this part of fibro or maybe cfs? Does anyone else have this happen to them during a flare? I have both cfs and fibro and this has been going on since the beginning over 20 years ago. I always notice that when my gums are broken out in these little blisters or sores, I am feeling my worse. Just completely out of sorts.