I wasn't diagnosed with Addison's when I was young. Though Dr Addison discovered the disease in 1849, testing and treatment for Addison's Disease was rarely done until the later 1990's, I was always tired and felt ill as a child, but since I never had a dramatic Addison's Crisis, nothing was ever done. My family does have a history of various auto-immune diseases and high stress, but it wasn't until I was older and had collapsed, that I began medication for Addison's Disease.
All of my life I have dealt with nausea that is a symptom of being over-stressed. I can confirm that not only does not eating increase stress, it can sure make you sick. When you don't have the vitamins and minerals your body needs to respond to the stresses it has to cope with, you do begin a downward cycle. It will also make you far more vulnerable to stress in the future. You will feel more and more ill until you finally collapse in exhaustion.
When you feel nauseous, it is one of the first warning signs that you are becoming over stressed. If you have Addison's Disease, you will have a Crisis if you do not begin taking better care of yourself. You need to cut out everything possible that is stressful to you, and nurture your body with plenty of good food and rest.
I know that is easy to say and hard to do. I have felt sick and exhausted so many times and kept "pushing on". What happened? I collapsed, of course, and wasn't able to do anything (blinking was even rare occurrence).
So even, and especially, when you feel nauseous you need to eat well. If you keep going, you can get to a point where you start gagging and vomiting up all your food. Not only is there a serious danger of becoming dehydrated (Addison's Crisis), but it is really miserable!
Balanced nutrition is essential when you reach this point.