arlou8 - It sounds like I experienced something very similar to you. My first 2 weeks of Tecfidera were very uneventful. My worst side-effect was itching. No stomach issues whatsoever. Then, at the start of my third week, BAM! I thought I had food poisoning because because it came on so suddenly. I got so sick and couldn't keep anything down, not even water. I lost 10 lbs in less than a week and got so weak and dehydrated. Then, it dawned on me that it might be the Tecfidera. I emailed my neuro and she agreed that I should stop taking it, see her in a few days, then repeat blood work before starting back up. Well, within a day of stopping, I could eat again. I'm afraid to start back up. Please let us know if you are continuing to have success with your diet change. BTW, for those interested, I have a cousin with MS also on Tecfidera (for a couple of months), and she hasn't had any problems beyond flushing.