What could cause severe, pulsating pain on the left side of my neck and head? i have pressure and ringing/muffling in my ear. also blurring of eyes.

Many things: The symptoms could be caused by a number of different things from migraine headache, TMJ and/or tooth issues, muscle strain, neurological issues, etc. This is something that a doctor and possibly a dentist will have to check out for you personally.

Get evaluated: Although your agoraphobia could be responsible for some of these symptoms, i would recommend that you discuss these with a physician to exclude the possibility of other causes which may require more urgent intervention.