Depending on your age, there may be various reasons for these signs and symptoms . The 'global' reason is likely low blood sugar or hypoglycemia. With no other factors offered in the question, low blood sugar is a common reason.
The fluttering movement under a persons skin is muscles trying to relax, but the nerve endings is basically what a person feels. The nerve endings a part of the muscles and the last thing to relax in...
This could be a sign of a serious heart condition. It may be that you are having a cardiac arrhythmia that is affecting your pulmonary function. You should see your doctor right away.