Could adrenal fatigue cause breathing issues? What are the symptoms? Any tests? Causes?

No. The term "adrenal fatigue" was invented in 1998 by a chiropractor. It DOES NOT EXIST. It's a new name for the old discredited notion of neurasthenia which was popular 100-150 years ago. Anyone who mentions adrenal fatigue to you is ignorant or a quack. They may even tell you that it exists & that doctors are foolish to deny it. It doesn't. REAL knowledge is power; arm yourself.