Need deep breathing frequently. To it.

I frequently need to take deep breath (Approx once in 1-2 min) since last one month whenever i am awake. And i feel like i am not satisfied. No problem while walking, jogging, taking staircases etc... No problem while sleeping... I have BP machine at home, and everytime i measures, it comes normal. Recently as suggested by my doctor friend i did vitamin B12 level test and it came 206, thus i took 4 injection for vitamin B12 as well. But still problem continues. Approx 2 and half months ago i undergone Acute Appendicitis surgery. At that time they did my chest x-ray, ECG etc... and it were normal. Recently i also did CBC/ ESR and it appeared normal. Local doctor told me that it may be because of stress or Anxiety. But right now i am not under any kind of stress and feeling relaxed. Please understand my problem and tell me what can i do to breath normally, smoothly as earlier. As sometimes i feel pain in Neck due to it.