My doctors have no clue what is wrong with me

[Cheredd]

I am a 42 year old retired Labor and Delivery nurse.  I suffered a neck injury at work and am unable to do strenous activites due to chronic pain.  I have developed sinus tachycardia in the last 10 months and have gone through a series of tests and seen many specialists.  All heart tests, blood tests and urine tests were normal including low blood pressure and low cholesterol.
The only significant result from the Holter monitor test was sinus tachycardia.  During a treadmill test I developed decreasing blood pressure as my heart rate rapidly increased with severe shortness of breath.  The test was stopped immediately and was sent to get a CT scan with contrast to rule out pulmonary embolism. This test was normal.
The second cardiologist to evaluate me noted abnormal response to carotid massage.  He said my heart rate decreased as expected but only for 3 or 4 beats then overshot the starting heart rate.  He was very confused and stated that he has never seen such a thing before.
I checked out completely normal with an endocronologist.  I am at my wits end!  I need help in finding out what is wrong with me.
This problem is causing me severe fatigue, headaches, and intolerance to exercise.  I am 5'4" and weigh 115 pounds.  I have exercised regularly since high school and have always had a low resting heart rate until 10 mos ago.
Any ideas on what could be the cause?

[Cheredd]

Yes, I should have been more specific.  I had an echo which was negative except for mild mitral valve prolapse.  In terms of the neck injury, I have has several MRIs and xrays, been to just about every kind of doc there is for that one.  I have 3 bulging discs, bone spurs, etc.  I don't think it is related, I just bring that up since one of my cardiologists thought a nerve pathway might be disrupted.  My neurologist thinks not.
Since it is a work comp issue I have to go at a very slow pace to get anyhing done there.
Thanks for listening.  I appreciate your time.

[ChickaBoom]

Did you have an Echo done?  If so, what did it show?

[Delee123]

Hi,

I think you should get that neck pain resolved first.  All of the other tests you have done are skirting this issue. An x-ray or cat scan or mri or something should indicate what is wrong with your neck ,  If they can't help you, see a chiropractor( But be careful, get a good one who may diaginose the problem)  

Sometimes a simple aliognment of the neck vertabrae is all that it takes.