I know this question has been asked before, but my issue is a bit different. I have both pip2.7 installed and working and pip3.4 installed and working (with my Python 2.7 and 3.
I'd suggest to uninstall and reinstall pip. Do so by running
pip
pip uninstall pip
Download the get-pip.py bootstrapper from https://bootstrap.pypa.io/get-pip.py and run
get-pip.py
python2.7 get-pip.py
or
python3.4 get-pip.py
respectively.