How to eat

I'm in my week 7 and my MIL comes often to cook for me. However I feel like I'm having an eating disorder whenever it's meal times due to my nausea, smells of delicious foods will trigger me. When she asks what I want to eat, just thinking of food triggers my nausea. And I really don't know what to tell her. Anyone with same experience? It's like some foods I can eat some days but after few days cant eat the samw thing aledy, some foods really brings vomit to my mouth.