I have vision loss in the left eye, severe migraines, stiffness in the neck, and staring spells. Why could this be? I do not have a tumor or aneurysm.

Loss of vision. What is your age? Is the vision loss constant or intermittent? Read the book, hypothyroidism, by broda barnes, from amazon.Com. He says 95% of migraines are caused by this. I had migraines for 30 years everyday, but not one since was started on Armour Thyroid 5 years ago. Try iodoral, an iodine pill that stimulates the thyroid. It is not a rx product.
Neurology evaluation. This constellation of symptoms is unusual and concerning. Migraines can certainly lead to vascular spasm and transient vision loss. A neurologist can certainly help to evaluate this and treat with medications. The stiff neck and staring spells are concerning-is there a loss of consciousness? Once again, a neurologist can evaluate for possible seizures.
Vision loss. See a doctor soon. Vision loss should be evaluated as soon as possible.