Hello ap rv: I'm sorry I cannot comment knowledgeably with regard to your concern. However, since this is your first post here on NeuroTalk, I thought I would simply welcome you.
I am not familiar with Oleanz. I have taken myself off of various antidepressants over the years. You wrote you were on Oleanz for a month prior to going off of it cold turkey. Based on my personal experience, I would have to say this does not seem to be a long enough period of time for it to be causing your anxiety. Of course, your having sustained a TBI could potentially complicate the situation. You might consider posting a Thread in the Traumatic Brain Injury forum here on NT:
https://www.neurotalk.org/forum92/
It is true that everyone reacts differently to medications. So perhaps your reaction is different than what I would expect. I do seem to be a person who is able to go off of psych med's without too much difficulty. I'm a member of NeuroTalk's sister website: PsychCentral. And, over there, I've read many accounts of members having quite a bit of difficulty getting off of various psychotropic medications.