Cause of rapid breathing?

For the past several months, I have been awakening (or wakened by) the sensation of very rapid breathing.  I've had full blood tests, chest x-ray, etc...  Breathing accompanied by a very sore left calf muscle which has since got somewhat better since Zoloft.

My Internal Medicine doctor believes this is anxiety related and has prescribed Zoloft, which I've been taking for several weeks now.  No change in rapid breathing when awakening.  Goes away during day and not noticeable when exercising (about 2 miles a day on tread mill).  Occasional pain in middle of sternum when taking a deep breath.  Occasional pain in lower left rib cage area.

I'm a heart valve patient (Ross procedure 3 years ago), 37 years old in good health.  Recent cardio visit before symptoms started revealed no issues.

Not only is this affecting my sleep but starting to affect my mental state.  Are there any tests my IM doctor might have missed?  What could these feelings be a result of?  This breathing issue has come and gone since my heart surgery, but is sticking around this time.  Taking Tylenol PM gives me a good nights rest.

Thanks

John

[National Jewish]

It is difficult to tell what the cause of the problem is with your description. One study that might help to find the answer is a sleep study. You would sleep in a lab and they would observe you, as well as take some readings. This would probably help to find the answer you are seeking.