Do you know what kind of parasites you have? Also, how did you find out about the heavy metal intoxication? Did you do some sort of test? What about the candida?
If you have liver problems, you shouldn't take Diflucan or any of the herbal antifungals just yet. You should try milk thistle first and even those coffee enemas if you don't feel queasy just thinking about them. After your liver is better, you can go on to take Nystatin which seems to be the safest for long-term use. I'm actually taking Nystatin at the moment. Not sure what to do about your parasite and heavy metal problem though. parasite cleanses with Black-Walnut and Wormwood can damage the kidneys and liver if you take them for too long. Depending on your symptoms, they could be die-off or the antiparasitics doing damage to your body.
Oh and if you plan on killing candida, you should probably take probiotics to ensure the yeast has no place to grow back. Your gut flora is like your immune system's secondary line of defense, and you'd want soldiers on your team.