I would also suggest getting another doctor's opinion. I myself, suffer from GAD- Generalized Anxiety Disorder. More simply put, whenever I am under any kind of stress or if I am overly tired and sleep deprived, I start to feel really nervous and my heart starts beating rapidly. It almost feels as if I'm having a heart attack. My whole body tenses up and I have trouble swallowing and breathing at times. I started having symptoms of anxiety disorder at the age of 17. I'm only 21 and they still have not stopped. It's very scary if you don't know what's happening.
I, personally do not like taking any medications, so I just learned over time how to overcome the "anxious feelings". Deep breathing and relaxation techniques seem to help the anxiety attacks subside. Just depending on your individual case, you may need to take certain drugs such as Ativan, which your doctor can prescribe for you. If you would like to do more research on it, you can do a search for anxiety/panic disorders to see if any of your symptoms match the descriptions listed. Don't worry yourself about it because it will only make it worse. Just know that you are okay and that there are many other people out there with the same condition. Wishing you the best.

Sincerely,

Dayna