Hello and welcome to HCM,
I don't know what your heart examination included (did it include a treadmill test?), but with your symptoms, and given that it was 6 months ago that you had your heart examination, I would strongly recommend you see a doctor again now. Some tests I would consider:
1. An EKG. A 12 lead EKG can give information about your heart rhythm and history of heart strain, but not always. However it is a place to start.
2. Possibly a
holter monitor to evaluate your heart rhythm over an extended period of time. This is a special device you wear for a day or longer to see if it can pick up on the irregular beats you described, that a regular EKG can miss.
3. Possibly a carotid doppler. This is an
ultrasound exam of your main neck arteries to make sure that blood is flowing normally to your brain.
4. A cardiac
stress (exercise/treadmill) test: This can show if your heart is experiencing strain.
Other tests may be recommended as well, such as possibly a
cardiac catheterization.
I am assuming that you did not have your current symptoms when you had your heart exam 6 months ago? IF you did have these symptoms 6 months ago at the time of your exam, and IF the tests I listed above were done then and were normal, then it probably is not cardiovascular in cause. However, I would still recommend you be seen again because your symptoms are significant.
There are other possible causes for your symptoms (musculoskelatal, gastrointestinal) but heart and vascular causes need to be ruled out.
So please do go in and get evaluated promptly.
I hope this information helps.