Could my seemingly unrelated symptoms be the sign of something larger?

Hello all,

I have been struggling with my health for the last 15+ years. I've gone from doctor to doctor, tried medication to medication, tried every type of therapy and nothing has worked. I finally have been accepted at Mayo and will be going to Minnesota this December. I want to share my list of symptoms:
Chronic diarrhea
Chronic nausea
Chronic abdominal pain
Chronic severe gas
Chronic acid reflux
Weight gain
Low libido
Abdominal distension
Metallic taste in mouth
Rash
Tachycardia
Anxiety
Depression
Panic disorder
Agoraphobia
Fibromyalgia
Chronic fatigue
Chronic joint inflammation
Chronic join pain
Brain fog
Confusion
Trouble concentrating
Forgetfullness
Hot flashes
Headache
Tremors
Sleep apnea

All are seemingly unrelated, until, my gastroenterologist(who has tested me for everything) now feels my IBS-D is the side effect of something much larger. The stomach issues are my primary issue and incapacitate me. The thought now is this may be autoimmune or some hereditary illness. Curious if anyone else has similar symptoms and how you manage to stay positive on the darkest of days.