My bass is being... weird. Due to a drastic humidity change, my action is out of whack. It's perfect down at the first fret, but at the 24th, it's about 1/4th of an inch higher than I want it. My uncle suggests either adjusting the truss rod slightly, or taking the neck off and making a wedge with something small like a matchbook to even it out. Which makes more sense. Is the truss rod the problem? I know I should take it to a pro, but I want to learn to do this stuff on my own. In PA, humidity change is constant, I want to be able to keep up.