I suffered a severe concussion almost 3 weeks ago and was knocked unconscious for nearly an 1hr. Am still having the same symptoms now, as I did when it first happened (blured vision, severe headache, nausea, vomiting, long term amnesia, confusion, loss of balance ect) There has been very little improvement if any. I am due to fly back to England on a 8hr flight from New York. Can I fly, or do I need to prospone my flight?