What Causes Severe Pressure And Headache With Nostril Blockage?

My sister suffers with all the classic sx of sinusitis that are described by lifescript.com data on sinusitis. She has seen 3 ENT, one wholistic medicine health care provider, and 1 Internist. They have done everything from blood tests to allergy tests to sinus xrays to tx with prednisone and hormones. She is not getting any relief from the severe sinus pain that creates tremendous head pressure/flushing of face/severe equilibrium problems/generalized malaise that overwhelms her whole body and feels very sick/large hard mucous plugs that occur-she is desperate for help. Would you suggest a consult with otolaryyngologist or where to turn?