I'm having issues with my Yamaha acoustic electric. I've played guitar for a while, but my tech knowledge is pretty limited. If anybody has any insight, I'll take anything you got:

When I first got my guitar (about three years ago), I could capo it without the strings being pulled sharp (even using a Kyser), and the guitar had no buzz (with or without a capo). Now, I get decent buzz on some strings (particularly D over the entire neck and higher up on the A), and the capo pulls it tight, even adjustable ones.

Two things to know: I changed strings a couple months back from whatever came from Yamaha to custom lights (yes, I had the same strings for 2 years), and I keep it tuned to D standard.

I was thinking it might need a truss rod adjustment, but I don't know how to reconcile that with those two issues. The strings being pulled tight makes me think it might have too much relief, but the buzz makes me think backbow. Not sure what else could get thrown out of whack when it went almost three years playing fine.

If anybody has any thought before I take it to a guitar shop, I'm much appreciative.