Obviously it could be stress. But it could also be the type of food you’re trying to sandwich the Tecfidera between. If the stomach issues continue, maybe try different foodstuffs. I know they say fatty food, but many people do manage to avoid too much fat and still take their Tecfidera. So, you could try toast or cereal, followed by Tecfidera, followed by yoghurt and / or fruit? Or toast then 'Tec, then more toast? Paolo (king of Tecfidera) swears by lots of toast with jam, no butter.
Do you have the same stomach issues when you take the evening dose? Or is that a bit more relaxed than breakfast? Perhaps you could try taking dose number one with lunch instead of breakfast? So long as there’s 4 hours between the doses, there no reason it has to be breakfast and dinner. And maybe you’re in more of a rush in the mornings, so feeling more stressed?
Theres certainly no point in taking a drug that you’re then going to vomit up, you may as well miss it out!!
I only took it for a few months (bloody lymphocytes took me off it), so I’m no expert, I just didn’t want you to feel like you’re trying to battle through on your own!