My thoughts. Sometimes this is just what doctors do if they think it is a one-time occurrence. They are not blowing you off. They do not want to perform expensive tests or prescribe a daily medication for a one-time episode. They expect the person to return and say that it hasn't gone away or gotten better after trying different things. This goes for things like pain, too.

Anxiety to me is a general feeling, and not an episode of hyperventilating. Hyperventilating sounds like a panic attack, which is set off by a fear that comes from our thoughts. Both are helped with therapy and things like relaxation techniques. Noticing what happens to set off the fear helps to understand it and to heal.