Sregan, are you a sufferer of CFS (chronic fatigue syndrome) or something similar? For them regularly nothing usually works, which is a bit disappointing. I know this from before.
Regarding the dose splitting, I don't think you will have any benefits from B5 if you're not feeling anything with that megadose. The dose splitting is just to make it more effective, take less, but more often.

One addition to the previous message: acetaldehyde is known also to cause a metallic taste in mouth. This sure sounds familiar to me.