It is very possible parasites can cause these symptoms--I have had most of them. Since the heart is a smooth muscle, it can be affected by both parasitic metabolites, and toxins coming from your own "localized" immune-cell, tissue cell secretions. The heart thing is not an issue with myself.
Tests. I would look for clues in the saliva. This is where you will find chemical anomalies.
It is also a way to check SIgA molecules. If they are elevated, there is likely a problem in the mucus membranes somewhere.
There are blood parasites to consider as well. I think mycoplasma bacteria, are almost always present with parasites [I'm sort of speculating on this, but chances are pretty high]. Shroom