I am new to acoustic guitar, I apologize ahead of time if I don't know what I am talking about.
So I got a AJ220SCE about 3 months ago, it play well out of the box.
But recently, I noticed that when I play on the high E string, at 13, 14 fret, the 15th fret tone will be played.
I assume the action to too low, so I fix it temporarily by sticking a piece of paper on the bridge.

Couple weeks later, the problem occurs again, now the range is 7 fret on, so I removed the paper and tried to look to see if I need to adjust the truss rod.
It seems it is bowing down like a U, so I tried tightening it, that make it way worst.
So I loosening it, it got better, but I think I loosen it all the way (it feel loose and then tight again, so I assume it is all the way)
Now it is playing the 15th fret from the 9 fret on.

I am not really sure what this is call, so I can't really google it. This is not buzzing right?

Any advice will be appreciated. Also, can humidity problem caused this? I usually leave it on a guitar stand.

You need raise the action a little more by slowing loosing the truss rod. It should take care of the problem if it doesn't you make take it to a guitar shop that does repair. You may want buy a new saddle, they just pop out and you pop them back in. You may want get a dehumidifier for you guitar as well. A few things you can do protect your guitar.
"Music became a healer for me. And I learned to listen with all my being. I found that it could wipe away all the emotions of fear and confusion relating to my family." Eric Clapton
This problem is usually caused by the fretboard lifting at the body join (frets 14,15,16), I tap them down with a flat piece of brass plate and a small hammer. The plate covers three frets. Sometimes it works and sometimes you have to remove the offending frets and flatten the hump, regroove and replace the frets. It's a common problem.
The truss rod will incidentally raise or lower the strings but that's not it's function. The truss rod adjusts relief for no buzz BEHIND the fretted strings then you raise or lower the strings by way of nut,bridge/saddle adjustments.
A temp fix for you would be to just raise the saddle.
First you set relief then string height at the saddle then string height at the nut then if needed at the saddle again.