First off, being Bi Polar is having a mental illness.
NAMI | What is Bipolar Disorder?
2nd, just because certain meds did not work doesn't mean it is not a mental problem.
And how do you know its not Schizophrenia? Do you know this because a doctor who knows about mental illness, says you don't, or is it your own personal opinion?
Also about the specialist saying, its not a mental illness, but spiritual warfare. Since he mentioned spiritual warfare, im guessing he is religious, probably christian. I was wondering, do you know his views on mental illness?
Also there have been times in which some Christians have misunderstood mental illness, and pointed the finger at demon possession/spiritual attacks when certain problems happened to people, when in fact it wasn't because of the supernatural. So there is a possibility this specialist is wrong about it being spiritual warfare.
Here is some info about Schizophrenia if your interested
Schizophrenia: Signs, Symptoms, Types, Causes, and Effects