Undone, I am so sorry you have to endure that pure hell. Don't ever go back on another SSRI/SNRI. make sure you know what category any new medication is in before you fill the Rx and take it. Effexor is the worst from what I understand.
There is also a very high risk of rebound depression when you discontinue an antidepressant. Talk to your doctor about adding Lamictal or a Lamictal/welbutrin combo in place of the Effexor, unless you are hypo/manic. Very very effective against depression. Lamictal is actually another epileptic drug, so it is also a mood stabilizer for us, but instead of being a downer type, it has a very effective antidepressant effect and is safe from causing mania, although that is possible, but it is rare. Welbutrin is effective and works differently is also less strong. Neither one has any withdrawl sx if you discontinue, and neither one has the sexual side effects, Yea!
Hope this helps,