I stopped taking a 75mg dose of Effexor twice now after gradual decreases over a period of months. About two months after completely stopping the drug each time, I experienced a variety of horrible withdrawal symptoms, such that I had to resume taking the drug. A year ago, I started my third attempt to end this drug, reducing much more slowly, at about 10% a month. I mention my experience to confirm that it is possible that what you are experiencing is the result of protracted withdrawal.
Are you familiar with withdrawal akathisia: ". . . a neuropsychiatric condition, characterized by severe agitation, restlessness and a sense of terror. . . . Patients report a very distressing subjective feeling of restlessness and dysphoria, and they often fidget, pace, rock and are unable to sit or stand still. However, akathisia can also manifest more subtly without obvious motor symptoms, typified by terror and a subjective feeling of restlessness.
"The pathophysiology is poorly understood . . . . This pronounced state of agitation can be mis-diagnosed as a manic state, an anxiety disorder, a panic disorder, a personality disorder, ADHD, health anxiety, restless leg disorder and functional neurological disorder, or a factitious disorder by clinicians unfamiliar with the syndrome in psychiatric drug withdrawal." [Excerpt from The Maudsley Deprescribing Guidelines by Mark Horowitz and David Taylor, p. 23-24.]
I understand little about it, but did experience some of the features of akathisia. It might be worth looking into for some explanation of what you have been feeling.