You started last week and are attempting full dose now? too much too soon! WAAAAAAYYYYY TOO SOON!
You also say that you feel you are eating ‘the right food’ but worry about gaining weight. This makes me guess that you have been advised to take the drug with fatty foods. this is nonsense.
FIRST - take a smaller daily dose. for week two, you should be on 120mg twice a day, at least 4 hours apart from each other.
SECOND - it does not matter one bit WHAT you eat, but HOW MUCH you eat. you can eat a zero fat diet; you can eat nothing but lettuce leafs and dry toast; as long as you eat enough to make you feel full by the end of it. this will help undermine the nausea.
THIRD - take an aspirin 30 minutes before your first daily dose. this will resolve (at least in part,) the flushing.
FOURTH - take a paracetamol if you get stomach aches
FIFTH - take an antihistamine if the flushing persists despite the aspirin
FINALLY - you do not have to take dose one in the morning. if you are not one for big breakfasts, take dose one with lunch instead. the ONLY RULE is do not take two doses within four hours of each other.
Tecfidera is an awesome drug; it is highly effective, very convenient and easily tolerated by those who take it. Sadly for some, those prescribing it can sometimes be about 18 months behind the times when offering good advice on how to take Tecfidera. Side effects of the sort you complain of, will make life awkward at least in the short term. you do not deserve to have to ‘tough it out’.
It is good to be on a DMD, but it is pointless if you are not inclined to stay on it. there simply is not a need to suffer such side effects. Good luck!