Definitely sounds like a humidity issue to me as well, though it must be pretty bad if you got enough back bow to make the first six frets of the Majesty completely unplayable. A truss adjustment and setup should cure the issue, providing you get the humidity stable. I've found that the Majestys take a bit of work in terms of getting a setup just right and are a bit temperamental, but that could just be the two I've had experience with.
I try and keep the room my guitars are stored in between 30-50% humidity. In the winter around here that can be a challenge and I'm filling up the humidifier every couple of days, but its worth it, as in extreme cases I can feel the fret ends out of the side of the neck. I've also bought a multitude of humidity gauges to find one that is accurate.
Keep in mind that truss adjustments take some time to settle. I generally make smaller changes and then check the next day once it settles in, and make changes from there if needed.
What I do to quickly check and adjust the neck relief is to place a capo or press down on the first fret of the lowest string, then hold the 12th or 14th fret down with my other hand and tap at the 7th fret. There should be just a little bit of gap there. If you have a capo on 1 you can get out some feeler gauges and measure. I forget right now what I generally keep the relief to. I think .006, but that's a wild guess without being at home and checking my equipment. When doing this procedure you can also look down the neck (from the headstock down) and there should be just a little bit of relief around 7-9.