) and anxiety
can be responsible for the shaky and jittery feeling. But in your case, since it was present before you started buspirone, I feel that anxiety is to blame and not the medicine. You may be wondering that if it was due to anxiety, then why it has not improved with buspirone. Buspirone gives good results in anxiety, but takes a few weeks to show the response. I feel that you should continue with the medicine without worrying. In a couple of weeks you will begin to see the results.
Hope this helps you. Best wishes.