The symptoms that you describe may be part of a spectrum of anxiety disorders. Though you did not mention the entire sympotms that you may be suffering, it is possible that you may have traits of Obsessive-compulsive disorder, hypochondriasis, generalized anxiety disorder. You may want to refer to the archives to differentiate one from the other.
Recurrent pulling of ones hair resulting in noticeable hair loss is defined as an impulse-control disorder called Trichotillomania. This ois accompanied by increasig tension immediately before pulling out the hair or when attempting to resit the behavior. Pleasure or gratification or relief is experienced when pulling out the hair.
Your meds - zoloft and xanax - are indicated for the type of condition that you have. However, especially with zoloft, you can feel a difference in your symptoms after 2-4 weeks. In the meantime, xanax is used to treat the symptoms if they are not tolerable for situations like being at work, etc.
You may also want to explore going into psychotherapy to help you cope with your anxiety.
Try to seperate the real fears from the irrational ones. It is NORMAL to be fearful of disease when you are getting tested because of
optic neuritis b/c of the connection between that and MS. The fact that you already have an anxiety disorder complicates it. You are taking off and running with it in your own head. In fact, for a person with anxiety, having a brain scan is really scary because you are already worried about something wrong in your head. People with anxiety tend to think about things and horrible outcomes that wouldn't cross the minds of the less anxious, and many of these things are not even realistic! Such as, optic neuristis is not usually a symptom of a brain tumor!!!Especially since its been mostly ruled out. Neither is anxiety! It is alright to be scared but don't connect everything together! It is good that you sought help b/c the extra fear from the actual illness pushed your anxiety to a more intolerable level. Now you have taken a step towards help for your overall anxiety. I hope that you soon feel better.