I have mdd and generalized anxiety disorder. what chemically causes these problems and can it cause a genital herpes outbreak?

Uncertain: Although monoamines (seritonin, norepinephrine and dopamine) have been theoretically implicated there is no proof of their direct role. Genetic predispositions, life experiences and other factors all seem to be important, but no unifying cause has yet been determined. The role of anxiety in outbreaks of herpes simplex eruptions (oral, genital, etc.) is also unclear although may be one factor.

Chemical causes.: Imbalances of neurotransmitter like Serotonin, Dopamine, Norepinephrine, Acetylcholine , Glutamate and Gamma-aminobutyric acid (GABA) are likely to be involved with development of depression. REF: https://www.health.harvard.edu/mind-and-mood/what-causes-depression. These issues could impact herpes simplex outbreaks.