hi..well, escitalopram and sertraline
have already been tried..also there is a drug called paroxetine
from the same group that takes care of panic disorder quite well..but before that, you are not receiving the optimum dose of the drugs you were prescribed..just use a single drug and only switch if it fails in full dosage, for example sertraline upto 200mg per day, after a considerable period of time which I think you were not advised..anyway, visit your psychiatrist
once again and discuss with these issues..also psychotherapy
may well help..so never lose hope..its a curable disorder..wish you good health..