It’s probably too late for you now, but for future refererence:
It’s not recommended to use pip to install system-wide packages! Use your package manager (pacman) instead.
I’d recommend reading up on Virtual environments to create a self-contained Python environment in which you can install whatever you want with pip, without it conflicting with your system down the road.
For example:
sudo pacman -S python-virtualenv
virtualenv path/to/my_virtenv
source path/to/my_virtenv/bin/activate
would leave you in your my_virtenv environment. Now, your Python interpreter will use packages from that environment, instead of your system-wide Python install. As long as you remain in this environment you can install whatever you want with pip, it’s not going to conflict with your system.
To exit the environment, just run the command deactivate. If you want to get rid of the environment completely, just delete the folder my_virtenv.
[Edit] Dalto beat me to it.