My e, G, and B string are making this weird dissonant sound, like if you were trying to tune a guitar by playing the same note on two strings and one is slightly out of tune, creating a noticeable dissonant tremolo effect, except I'm only playing one string. It becomes a lot more noticeable as you approach the 5-7th frets- what's the problem here? Do I need a truss rod adjustment? Is it a pickup issue?

Thanks for any help- the guitar is an Ibanez RG2EX1 (well, RG2EX2 according to the back of the headstock).
This happens to my high E string on the 12th fret and above when the strings have been on for ages, and rusty/dirty (not that I don't clean them though). You may just have to change your strings if it's been a while, or clean them if you haven't for ages to see if it makes a difference.
Huh, that actually makes a lot of sense. My E, A, and D strings are the three most recent to break, and I do the cheap college kid mindset of "you only need new strings if one breaks!" I'll try doing that soon and see if that helps, thanks!
My epi les paul started doing this. Even when I put new strings on, my high E and G string do this weird dissonanc/buzzing/shaky sound all up the fretboard. I figured it had to do with a faulty bridge, maybe something to do with the saddles, or maybe the nut.

I never figured it out, and it's on consignment at a local guitar shop so I can get some money to buy a new guitar.