I presume that you had raised a question on this forum regarding sleep issues before.? Sleep as you know is the state of calm & peace, and with breathlessness & racing thoughts it's hard to go to depth of this calm. Continuing with same psychiatrist who had prescribed Clonazepam or consulting another psychiatrist should help to get prescription for medicine which should help better. Additionally have you considered undergoing counseling/therapy..? Medicine is not the only solution in any discomfort related to thoughts & emotions, therapy can help you understand the source of your anxiety, make sense of the racing mind & overcome the anxiety. Any competent Psychologist or Psychiatrist should be in a position to help you here. Take Care.