Ornithine, milk thistle &, some say activated charcoal, can help with die off. Drink lots of water. Also daily low enemas (follow up with active cultures for probiotics in things like yogurt & kefir and take prebiotics) speed up the process and help wash out the dead bodies which release toxins.
Die off will still happen though. But you'll get through it. As for the heart palpitations, I have not heard that either parasites or candida cause those and even if they can there is no way to know if they are the culprits.
Diagnostic testing seems the best route for the heart concerns.
Are you drinking too much caffeine? Any other meds or supplements that could be causing the problem? A lot of stress? (If so see stopthethyroidmadness site on Those Durn Adrenals & see Dr. Michael Lam's site.)