The dose you take should be ultimately decided by you, not your doctor, since you are the one experiencing the side effects of such a large dose, which does stimulate you too much. Rather than going off altogether, I would ask your doctor about going back to the original dose. If you go off altogether, it should be over a three week period. But you can reduce to the original dose almost overnight without any side effects, but to be safe, reduce it to that dose over a week's period.
I'm sorry, Dr. Glenmullen has another book out called "Prozac Backlash" that refers to the Parkinsons-like effects. But both books by him are really good!
If you are going to stay on Zoloft I would recommend the least effective dose. I have read in books about the "parkinsons"-like reactions in higher doses. Can I recommend Dr. Glenmullen's book "The Antidepressant Solution" ? He speaks about these adverse reactions, such as twitches and tics. The book's tagline is: "A Step-by-Step Guide to Safely Overcoming Antidepressant Withdrawal, Dependence, and 'Addiction'". I was placed on anti-depressants for 11 years... being told I needed to stay on them the rest of my life. I don't agree with that assessment since there is no physical disease that indicates I am permanently in need of medication and so I have just recently tapered off. Withdrawal symptoms are very unpleasant, but I think once the originally-diagnosed issues are dealt with, then the medication is no longer needed. I am hoping my body & brain can cope after being on meds for over a decade! My most recommended book, however, is "Will Medicine Stop the Pain?" by Elyse Fitzpatrick. It is a biblical-based approach to troubling emotions, and helps you understand the physical aspects of depression/anxiety and how medications actually work. It even talks about how doctors prescribe more & more medication to your regimen to "deal with" symptoms (i.e. anxiety) that are actually side effects of the antidepressant!