You say you were taking Zoloft at 2Mgs a day? I didn't even know Zoloft came in such a low dosage. I used to take Zoloft at 200Mgs a day. Lowest dosage is 50mgs a day and even that dosage is too low for most people.
Lexapro is an SSRI like Zoloft, Prozac, etc. Sometimes it can be a little trial and error before one finds the right medication in my experience. They all effect us in certain ways. With this, are you seeing a counselor? I believe the most important step you can take is to seek counseling and learn about your anxiety. Knowledge is power in confronting this...keep us posted!