I just realized that my coworker has merged my feature branch into the master branch in Github, while I have been continuing working on my feature branch on my local machine
You can git stash those changes while you create a new branch. git checkout < then git checkout -b <.
You've got a clean copy of master now, so let's get those stashed changes with git stash pop. Now you're back to where you started, with all your already committed changes in the trunk and your new changes ready for commit.