Hi. I am asking on behalf of my daughter. She has shallow fast breathing when she lifts or walks. 31 years old. Doctor has checked X rays and there is no sign of problems with her lungs. She has taken pristiq medication but stopped 1 week ago. She has a cough...some yellow sputum but has been on a number of antibiotics for this. The breathing, faintness and dizziness don't seem to be associated with anxiety she says. She has worked the whole time but work is becoming difficult and she is not keeping up the fast rate required.