Probiotics: When you start probiotics, you can almost expect to get more diarhea and some discomfort. That is normal and hang in there, it will pass. I had the same problem and waited until my flare got a bit more under control and tried the probiotics again and voila!
Just a suggestion: What I do regarding fiber intake is to take a cup of yoghurt and mix it with one cup of Fiber One cereal - only if you can/like yoghurt and not flaring too much. It is tasty and only half a cup of Fiber One will do, too, but I like the whole cup. I don't know if the Fiber One is gluten-free, so you might want to check on it, but it helps me.
Sorry to hear that you feeling well and out of the flare on Christmas must have been a lucky fluke for you, was hopeful that you gave the flare the stink eye for good this time. I am fortunately doing very well and flare up seems to be gone - I hope it is fair and safe to say this is the case with almost three symptom-free weeks, off Prednisone and on 6-MP. Good times anyway!
Hope you find a solution for you soon, I keep my fingers crossed!