thats all in the neck. has this just started or what? guitars are extremely susceptible to climate change, so if this is new, thats problably your problem. the most simple solution is the next time you restring it, get some murphys oil or lemon oil or linseed oil or something, and coat the fretboard with it, wait for it to absorb, wipe the residue/dirt off, repeat like 10 times, and see if its straightened at all. Also get a humidifier, so this never happens again. Where do you live, is it dry or humid?
if its been like this a while, youll want to adjust the truss rod. If that doesnt work, your relatively ####ed. At that point, you can either get into the process of reshaping, etc, or just buy a new one. thats pretty rare though, its problably weather or truss rod.
