Trazodone metabolizes into a organic compound that is psychoactive and can cause anxiety. It is quickly metabolized into a benign one, but if you are a slow metabolizer it wil take more time for your body to eliminate it and may cause you troubles. This psychoactive compound is metabolized by CYP2D6, the same isoenzyme that metabolize most of AD except bupropion (I don't know about MAOI). It is the main metabolizer enzyme of SSRI, SNRI and TCAs. If you take them together the enzyme will be to busy to metabolize either the AD or the psychoactive compound of trazodone, so you are more likely to get side effects.

Have you tried gabapentin, pregabalin, old antihistaminics, benzos with antidepressant proprieties or antipsychotics with antidepressant proprieties that are not as sedative as seroquel is?

Crazy, inside and aside

"Outwardly: dumbly, I shamble about, a thing that could never have been known as human, a
thing whose shape is so alien a travesty that humanity becomes more obscene for the vague resemblance."
I have no mouth and I must scream -Harlan Ellison-