Nausea in food sensitive people is a mystery as it often seems to come for a while and go away for a while for no reason that is related to other symptoms or a food you may feel is a cause. It is important as means you do not feel well. It happens most in those with IBS. People describe “feeling off”, feeling “bad” or feeling like having a rest and hoping to get some sleep and wake with it gone away. In some it may be connected to motion sickness which makes it worse. It affects your appetite as it means you do not feel like eating. So you eat less and your weight can drop. As with other symptoms do discuss it as a separate symptom with your doctor, and separately check if nausea increased on some new medication. Ask what meds (such as those for motions sickness) may help decrease it. Do make sure that there are no smells you find unpleasant around when you want to eat, and avoid cooking food that you know you will not feel like eating. Your nausea may also be affected before eating by the temperature and therefore the smell, and by the flavour during eating. You may learn that cold food is more acceptable.
When nausea is bad just eat what you feel like and have as much as you can of the foods you feel like eating. Then when you go through a good phase catch up by eating normal good food so you recover any lost weight. I am emphasising that nausea matters so you feel supported in deciding to ask your doctor for help and not just putting up with it. It is frustrating to be told your nausea is probably all in your mind. It may not be in your mind but it may be in your brain. Everyone feels nausea near a dead animal. It is a reaction in the part of the brain that responds to the bad smell. Some food sensitive people notice smells more but each notices their own particular annoying ones and each have their own symptom. So some can feel nausea for reasons we do not yet understand.
Fortunately for many the severity does decrease with other diet changes after the diet trial and your strong smell sensitivity may also decrease.