Doctors rarely start you out on such a high dosage, they prefer to start with the lowest dosage and if needed increase it with time. Also, even lay people know that you should never just stop these medications cold turkey.....bad withdrawals. Psychiatrist are the most knowledgeable when it comes to these types of medications, I would make an appt. to see one and hold off on starting such a high dosage until you speak to him.
yes getting a second opinion sounds like a good idea, that is a high dose to start on but i am not a doctor. I have never heard of a doctor saying stop cold turkey from these types of medication. To me cold turkey is a bad idea, because of withdrawals and these are chemicals you are putting in your brain and then to suddenly stop you are more likely to go into another relapse of depression/anxiety.
Best of luck,