You sound JUST LIKE ME. The only difference is that I am under the care of a doctor, a psychiatrist, and 2 counselors... and I have a positive diagnosis for underlying mental issues. I am properly medicated. These are the things YOU need.
It definitely could be physiological, but that doesn't mean that's easy to find and diagnose. Things that could cause this are fibromyalgia, chronic yeast infections, chronic fatigue syndrome, hidden viruses, parasites, die-off of beneficial organisms, thyroid dysfunction -- so many possible causes that are all very hard to diagnose except by a specialist that really cares to exhaust the possibilities. But it's also completely aligned with depression. If you can find one and can pay for one, as they almost never take insurance, there's a type of psychiatrist called a functional physician -- they understand mental illness, but first look for all pertinent physiological causes before diagnosing it as mental illness.
If you ever need someone to talk to, please message me.
I'm not sure if I can help unfortunately, but I have the exact same problem. So I can understand what your going through. Your not alone...........