I am in need of a gold standard dataset with features all of the mental disorders such as Depression, PTSD, Bipolar etc. and their symptoms. For example, symptoms of depression are back pain, apathy, hopelessness, fatigue etc.
You are going to get a more reliable database by looking at symptoms in the first place. If you can still find them, leaf through old journals from last century where reasonably complete lists of symptoms and patient complaints were sometimes compiled, eg in the psychosomatic literature..
If you're operating within North America, DSM-5 is best. Internationally, ICD-10. If you prefer textbooks, latest edition of Saddock and Kaplan's handbook is good.