The reason you find the three forms of Vit. C too stimulating is because your body can't clear their byproducts and metabolites (what's leftover when your body takes the good stuff.) The body is decompensated from AF or from whatever malady caused the AF, and has a hard time breaking things down.
I've spoken to Lam about this (I'm a "client" of his) and he says it is very, very common. I know of a dozen folks here on CureZone who have similar issues with Vitamin C.
The trick is to take minute amounts of the Vit. C over time (ask Lam for guidance on this) and get that adrenal reserve built up.