I was doing some late night wikipedia'ing.
Veterans of World War I came back from war and experienced what they themselves termed as "shell shock". Soldiers were involuntarily crying, shivering, going blind, developing physical maladies that doctors could not explain.
Soldiers suffering were initially seen as weak and complaining. But finally the overwhelming number of cases and undeniable symptoms forced the medical world at the time to come up with a formal diagnosis.
So when you are thinking (like I do sometimes) why do I feel this way? What's wrong with me? Am I crazy? NO you are not crazy, it's a perfectly normal reaction to abnormal events.