NOT everyone is gluten intolerant, only people with specific conditons are. You can get sick from too much of anything, including water, that doesn't mean you have a gluten allergy because you gorge yourself on bread.
most of those things are symptoms of other conditions. the foggy-feeling in your brain and depression are symptoms of a number of disorders that a lot of people have, namely seasonal affective disorder which is caused by lack of vitamin D and insufficient exposure to sunlight.
Insomnia can and is caused by using electronic devices, the blue light from the monitor inhibits melatonin production.
and everyone suffers mood-swings from time to time, some more than others.

Tell me, did she happen to buy a paleo-diet cookbook or something similar?