I agree with afv011. You need to do some testing to determine whether the fault is with your Touch or the ebook. Looking at the book with Sigil would be good. Testing it with other readers would also be good, of course.
However, it can be really hard to diagnose something like this, IMHO. Say it worked fine in Calibre Reader or Nook for PC. Therefore it would seem that it was your Touch device that was at fault. But you'd still not be entirely sure that perhaps there is something wrong with the ebook, but that what is wrong with it didn't confuse Calibre or Nook for PC enough to do that jump-back thing.
Of course, if the ebook misbehaves in the other readers, then you know it is the ebook and not the devices.
I actually do think there is something wrong with the ebooks and not the Touch. No one else has ever reported this happening (as far as I know), so it doesn't seem as though it could be a Touch software thing, and it seems really unlikely to be a hardware thing (I mean, how would the touch screen or page forward button be causing this?).
Let us know what you find out with some testing.