Over the past couple of weeks I have been experiencing a sensation where when I am standing up, I feel as if something is pressing down on the upper part of my diaphram and making it difficult to breathe. It is worse in the morning but seems to get better toward the end of the day. This condition has become so worrisome that I am unable to drive for fear of hyperventilating. I am not sure what to do here. Any good advice I'd really appreciate. Thank you.