You're probably getting ready to make the top of the foot. It's a pretty common way to handle that.
Hook on the new color, however you need to do it, and knit as if you were going to do a round, but stop after as many stitches as the pattern tells you to. Turn the work, just as if you were working on two straight needles, and do whatever the next row says.
If you're using all the stitches, you'll turn rather than going on where the round ended. If you're not using all the stitches, you'll work back and forth on a few until you make the top of the foot.
Oh, and if that is the top of the foot you've reached, the pattern may tell you to pick up stitches along the edges of the flap you make, then will often have you knit in the round again. It really does make sense. You'll see as soon as you try it.