Richardt--I think it is extremely important to determine your daughter's current position with a thorough physical examination while experiencing this exacerbation or flare-up. We hope she has a caring medical professional.
As to treatment, I am not a believer in any of the CRABs, based on my own experience with C (Copaxone), no experience with R (Rebif), a long 7 years with A (Avonex), and 4 years of B (Betaseron). In my opinion, these drugs were of no benefit to me. I hope interferon has been been helpful in your daughter's case. My doctor tells me, "But we don't know how bad you would be right now if you hadn't taken them." The problem with this disease is that it naturally has periods of remission.
If you have not already started a personal MS library, I recommend two books: "Multiple Sclerosis: The History of a Disease" by T. Jock Murray, OC, MD; and I think "The Multiple Sclerosis Diet Book" by Roy Swank, MD, PhD and Barbara Dugan is the second good book to have.
In that thorough physical exam, ask for any kind of blood test possible (including cortisol, thyroid hormones, and a fasting serum insulin test--I am known at this website to be obsessed with insulin!).When she has an MRI, ask that the radiologist make a special note of the sinuses. Many with MS report sinus problems (including myself). I am now sure that mucus (from viruses or allergies) causes insulin production due to dense "sugar-coated" mucins. Ask for a copy of all her test results for your own file.
I encourage everyone with MS to eat a healthy diet. In my opinion, this means removing all sugar, all artificial sweeteners (These promote insulin production more than sugar.), all trans fats (These also increase insulin.), and white flour (in fact, all carbs so far as possible) from the diet.
Welcome and best wishes.