I have read that a metallic taste in the mouth is from parasites dying in the body. But because of the corresponding mental symptoms and anxiety I believe the unithiol sulphur bonds of all the garlic are redistributing heavy metals in your brain and nervous system, as you suspected. Might want to be cautious for now.
The sore stomach could be an ulcer- did you take the large quantity of garlic on an empty stomach? If the sore stomach feeling could very well be gas from protozoa die and/or fungal dieoff in your stomach and small intestines as well, as you also suspected.
Be safe bro- i don't want to lose my good curezone friend to detoxmortification :)