I couldn't believe that parasites were a significant cause of my problems, either, so I get it.
In fact, I resisted parasite cleansing for a long time because it simply didn't 'make sense' .. I'd had a stool test that was negative and just couldn't imagine how some 'worms' (that didn't show up on a test; how little I knew!) could change my neurochemistry so significantly - but they (more specifically, their consumption of micronutrients and production of toxins) do. I resisted until a doctor in Tijuana diagnosed me and outlined a treatment plan.
Parasites can infect anyone at any age, and, unless eliminated, can persist in the body forever once they've established themselves. I've had nearly all of the symptoms you've listed, and nearly all of them clear up immediately following an anti-parasite regimen.
Also, this may not be obvious, but parasites particularly affect those who are significantly above average in intelligence; they're more sensitive to changes in neurochemistry, their brains consume more energy, and their bodies require more nutrients (macro and micro) to produce that energy and regulate their neurochemistry. Any significant disruption in nutrient assimilation/processing, metabolism, energy production, etc. (which a parasite infection can cause) essentially throws a wrench into everything.
And, finally, it feels like you're saying (paraphrasing) 'I'll try the parasite cleanse so I can say I tried it' as if you're just going to 'give it a shot'. I imagine, having read curezone, that you realize it isn't something you just do once and that many have to 'fight' over a period of time before getting ahead of them, and I encourage you not to quit early. That said, if you try it and it doesn't help, it doesn't help.
Are you planning on trying pharmaceuticals or herbs, if I can ask? I've tried many, many herbal formulations and had some success - they do work - but now prefer pharmaceuticals for efficacy.