If you already have troubles with a bit of lemon and olive oil, don't jump into full Liver Flushes straight away. Instead, I suggest you do daily coffee enemas, and drink beet juice. Start with low dosage, 4ounces maximum at a time, as beet juice is a very potent liver cleanser.
You can start taking activated charcoal also.
How is your diet like? You need to make sure you're eliminating properly (at least twice a day). Use psyllium and/or ground flaxseeds.
Once your bowels are working properly, you can jump into a more agressive regimen to eliminate fungus and parasites.