I know that for many ADs, you can feel down before you feel better. I think it's a recognised side effect of some?
From Cymbalta/Duloxetine info pages re side effects:
Nervous system
Very common (10% or more): Dizziness, headache, somnolence
Common (1% to 10%): Dysgeusia, lethargy, paraesthesia/hypoesthesia, tremor
Uncommon (0.1% to 1%): Convulsions, disturbance in attention, dyskinesia, extrapyramidal symptoms, myoclonus, psychomotor restlessness, restless legs syndrome, trismus, syncope
Rare (less than 0.1%): Akathisia, dysarthria, gait disturbance
Postmarketing reports: Intracerebral bleeding, seizures upon treatment discontinuation, serotonin syndrome[Ref]
Psychiatric
Antidepressants may have a role in inducing worsening of depression and the emergence of suicidality in certain patients during the early phases of treatment. An increased risk of suicidal thinking and behavior in children, adolescents, and young adults (aged 18 to 24 years) with major depressive disorder (MDD) and other psychiatric disorders has been reported with short-term use of antidepressant drugs.
Very common (10% or more): Insomnia
Common (1% to 10%): Abnormal dreams, agitation, anxiety, sleep disorder
Uncommon (0.1% to 1%): Apathy, bruxism, disorientation/confusional state, irritability, mood swings, nervousness, poor quality sleep, suicide attempt
Rare (less than 0.1%): Aggression and anger, completed suicide, hallucinations, mania, suicidal behavior and ideation[Ref]