What Causes Pressure Behind The Forehead And Fatigue While Suffering From Anxiety?

My daughter, now 8, had a rather sudden onset of change in behavior at age 5 1/2 years old. She has increased sensitivity to clothing, sensation, and noise. Has been diagnosed with anxiety, ADHD, and sensory processing disorder. Now she has been reporting a weird pressure like sensation behind her forehead, complains of fatigue all the time , has had noted memory deficits, mood and anger outbursts, cognitive and learning decline in school to the point that speech therapy is treating her for cognition, and the school has initiated an IEP. She has muscle weakness and fine motor difficulties, with OT treating her at school, and her physician recommending further PT. She complains of intermittent stomach pain always around her bellybutton that resolves pretty quickly. She has difficulty with concentration, staying on task, and following even one step directions. Her grades decline drastically throughout the school year last year, even with multiple supports in place. I m questioning the possibility of a physiological cause as the root of all these random symptoms. None are severe enough on their own to draw attention, but combined, they make her life pretty difficult. Her doctors are quick to assign a psychological diagnosis, but like I said, onset was pretty abrupt at the age of 5.5. It was like we suddenly had a different child. And she has just declined since then.