The vast majority of the known diseases-those which have a known clinical course and diagnostic tests, were described by physician who lived 100 years and more ago.
Our environment has changed tremendously since then, but we still stick with those old descriptions and what doesn't fit or is "unexplained" is thrown into the rapidly growing basket of "emotional problems".
"Functional", "low threshold" and many other terms are being used to describe those entities. They all replace the true term which is- "we don't have a clue, and have no intention of bothering to try and understand what doesn't appear in our books" . Physicians are seeing more and more patients with obscure/vague symptoms. We are also seeing more and more disease of the elderly at a much younger age. I personally think that this is the sad result of the enormous and cumulative amounts of toxic substances we ingest, inhale and absorb through our skin in a world which is becoming more and more synthetic and further away from what our body should have been exposed to.
A colleague recently told me about a mouse in which there is a mutation in one protein, which is involved in DNA repair. This mouse has normal strength but develops fatigue rapidly. It is still not clear what is the exact mechanism by which this happens, but there are apparently some metabolic changes.
I was quite fascinated by the way in which a seemingly unrelated protein could cause a myasthenic like weakness. At the same time I told him that there is no doubt in my mind that if a person with a similar mutation was seen by a neurologist he would have been diagnosed as suffering from "emotional problems".
One protein which is altered can lead to significant and remote changes. Such alterations can be from birth or as a result of modifications by various substances or immune processes. many times it is a combination of genetic propensity with environmental exposure.
But, such alterations may be reversible.
Dietary and environmental changes will not lead to improvement within a few days. It can take weeks to months or possibly even years. But, I personally believe that this is what you need to do and not "search" for some obscure emotional problems.
You may (or may not) find this helpful:
http://www.youtube.com/watch?v=KLjgBLwH3Wc