As dm has wisely said, these symptoms CAN most certainly and ARE frequently part and parcel of anxiety. But you have left out much information surrounding these episodes. When do they happen, what is going on in your life when these symptoms appear? Has anything rather traumatic happened in your life recently, and that could include something from a year ago that is just now getting to the front of your head. How long do these symptoms last? Does anything else happen to you while they are going on? Tell us more about yourself so that we can get a better picture of the things you are dealing with in your life.
But even before we have that information, I strongly agree with dm that you should get in to see your doctor as soon as possible and let him/her know what is going on with you. You need to have some physical things ruled out before we can rule in anxiety as your problem.
Please keep us posted and if you have any more questions, ask as many and as often as you want/need to. We are always here!
Peace
Greenlydia
Could be, you don't say whether it is constant or comes and goes. Have you been checked out by your doctor to make sure you are physically ok?
Rapid heart beat and breathing difficulty is definately symptoms of anxiety, but more serious causes should be ruled out first.