Welcome to Health Care Magic
You will have to repeat the ambulatory monitoring (Holter) again.
The study could also be extended to 48 hours.
Further management is dictated by the results of the test.
You may need ECHOcardiogram
/ Treadmill exercise ECG (TMT) / Laboratory work-up
If there are no clues and if you are still bothered by it to the extent of interfering with life style, there are advanced techniques of investigations of increasing complexity like Electro Physiological Studies (EPS). The test is the gold standard, but it is invasive and has a minimal risk – it is not generally done unless there are compelling indications.
You should see a cardiologist and keep seeing.
Wishing speedy recovery