My strings were very old and rusted so I changed them, but after only a week they look like they've been on the guitar for a least a month. wtf? The only thing I can think of is that maybe there was dirt on the fretboard that is now stuck to the new strings or something. Strangly enough it looks kind of like rust but since I whipe all the sweat off the strings after I play this is strange. Anyone know if it's the fretboardirt or maybe something else? I use d'addario 10s btw, and never had problems like this with 'em before.
Try cleaning your guitar before you changed the strings next time.
nah... it happens to me all the time. i live in alabama and what causes the rust is the humidity. when you are done playing, try covering the neck and strings with any type of cloth or an old sock or something. you still need to wipe the sweat off the strings too. they will get rusty, but it will slow it down quite a bit.
Clean the fretboard when you change your strings again, and wash your hands before you play.