I have vestibular migraines/chronic daily headache and have found venlafaxine er to exacerbate it. i'm considering cross taper to a tca, any thoughts?

Venlafaxine: Is a serotonin and norepinephrine reuptake inhibitor. Works well for some. Talk to your doctor about other options like Amitriptyline or Topiramate. You have a complex problem, best solved at your doctors office.

May be great change: Actually, with certain headaches like chronic migraines and chronic daily headaches like yours, one of the long term prophylactic treatments IS putting the patient on a TCA, so that might be exactly what you need anyways. Venlafaxine is notorious for either causing or exacerbating already existing headaches so I would certainly recommend getting off that. Trying the TCA is a great next step.