Here's one of your last threads that would be relevant for you:
http://www.medhelp.org/posts/Anxiety/lexapro-increased-my-anxiety/show/2093970#post_9931328
The most common "start up" side effects are a "jittery"/"keyed up" feeling, an increase in anxiety, GI disturbances (nausea, sometimes vomiting, diarrhea, lack of appetite), sleep disturbances, headaches.
The side effects usually start to improve after a week or two, then completely resolve shortly thereafter. I know it isn't easy, but it's best to be patient and give it some time. It's not common to feel a little worse before you feel better. Keep your doc informed also.
Keep in touch!