First of all, keep in mind that I am unable to diagnose you because I am unable to examine you, this forum is for educational purposes.
The symptoms that you describe could be due to depression, but they could also be explained by migraine headaches. A sense of
confusionConfusion
Delirium and feeling "spaced out" is
commonCommon cold in migraine sufferers. Also the symptoms of feeling like you may pass out and "head spinning" are common in a migraine varient called basilar migraine. That being said, the symptom of depersonalization is often due to depression. I would recommend an MRI of the brain (to evaluate for a structural cause of your headaches) and an EEG (electroenecephalogram-brain wave test) to evaluate for seizure activity (that can also leave you confused). I would recommend that you start a daily headache preventative medication like Elavil, zanaflex, topamax, etc. I would also recommend that you see a mental health care professional, treating depression is more than just starting a drug, it requires a team of supporters inculding therapist, counselors, social work and drugs.
I hope this has been helpful.
Don't depend on a single doctor, be persistent, and if you feel something is wrong, trust yourself, and be persistent about your care.
Have the doctora checked your thyroid levels? If not you need a free T-3, free T-4, TSH, & thryoid antibodies, which are TSI & TPO.
I have Grave's disease & thyroid eye disease & the symptoms you mentioned in your post are much like what I experienced.
Good Luck & God Bless, TJ