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From his symptoms and normal investigation he is appear to have depression
. In history there are many symptoms related to different body systems, which is infrequent in physical illness of one system.
Hope, he has been investigated by routine investigations to rule out physical illness specially anemia, thyroid function test and liver function test.
From the history there is no definite neurological deficit. It will be better concurrent opinion from psychiatrist
, as depression can also present as loss of appetite, weight loss
and body pain
Wish you Good Health and all the best.