NAC showed strong positive effects first few weeks but diminished function afterwards

Some background: I've been doing horrible this past year after I burnt myself out working over a 12 month period, I was really wired the first six months after quitting work, didn't get good sleep at night, and was able to go out and do things with friends as well as read books on medicine and what not but then about four months ago my health altered and I haven't been able to read or leave the house but a few days a month, however, I get good sleep and don't feel wired anymore but the fatigue still remains and is more prominent than ever.

So I started taking an NAC supplement containing 600mg's of NAC as well as small amounts of Selenium and Molybdenum back in early july and the results were spectacular, at the time I was only taking one capsule per day for 5 days out of the week and man that first week was great as the NAC went strong 4 out of the five days, The week after that the effects were great some days and not there other days, I tested the NAC for a few more weeks like that with results not coming as powerfully as before, I switched to taking 3 NAC capsules everyday(instead of 1 capsule per day, 5 days on 2 days off) around 3 weeks ago or so and nothing really changed. The effects still sort of come and go and when they do come they aren't nearly as potent as those first 2 weeks, things were good then, I had energy in those few days which i used to read and enjoy myself without painful fatigue crushing me and brain fog screwing with my mind as heavily as it does all the other times.

I wonder what could have happened, I'm thinking about ordering an Amino Acid test to see what my levels are since NAC is N Acetyl Cysteine with cysteine being an amino acid that's important for production of Glutathione and Metallothionine; anyone ordered one of those tests before or know where I could get one? I started taking NAC after reading about it helping some individuals with copper toxicity issues, and, since I have now had four hair test come back showing extremely elevated levels of copper, I figure it is a serious part of the problem.

Anyone else have experience with NAC?