The grapefruit seed extract is an antifungal. It possibly caused candida die-off symptoms, which can also be a sudden release of heavy metals when the yeast is being killed. I wouldn't advise antifungals if you're dealing with mercury.
The nanonized chlorella, cilantro and probiotics in NDF is really only safe to take once when bowels, liver and kidneys are functioning better. Parasites is also an area that might need dealt with before detox. And it's becoming more well known that a high level of ammonia can cause lack of response to treatment, plus severe side effects.
A lot of info there, and it may not be relevant with you. These are things i'm having to deal with.