I've had an ongoing issue with my classical guitar. The third string (nylon) always buzzes on first, second, and third fret. While we're at it, the sixth string (wound metal over nylon core) buzzes on second and third fret. I've checked my positioning and pressure, and the problem isn't me.
I did string this guitar myself a few months back (standard method, not using ball-end strings), and I've been having this issue ever since. What is going on? Could this have to do with the stringing, or a bad string, or something else entirely.
As a note, all my strings are strung the exact same way, and I never get this problem on any other string or fret. Just the ones mentioned above. Any idea what is causing this?