pip is no longer updated Is the _internal module missing?

It's been a while since when I installed modules with pip it tells me that I should update it. However, when it is updated, nothing changes:

mike@mike-thinks:~/Programing/Rasa_tutorial/moodbot$ python -m pip install --upgrade pip
Collecting pip
  Downloading https://files.pythonhosted.org/packages/0f/74/ecd13431bcc456ed390b44c8a6e917c1820365cbebcb6a8974d1cd045ab4/pip-10.0.1-py2.py3-none-any.whl (1.3MB)
    100% |████████████████████████████████| 1.3MB 720kB/s 
Installing collected packages: pip
Successfully installed pip-8.1.1
You are using pip version 8.1.1, however version 10.0.1 is available.
You should consider upgrading via the 'pip install --upgrade pip' command.

mike@mike-thinks:~/Programing/Rasa_tutorial/moodbot$ sudo -H pip install --upgrade pip
[sudo] password for mike: 
Traceback (most recent call last):
  File "/usr/local/bin/pip", line 7, in <module>
    from pip._internal import main
ImportError: No module named _internal

Here are the versions of Python 2 and 3 that I use:

mike@mike-thinks:~/Programing/Rasa_tutorial/moodbot$ python -V
Python 2.7.12
mike@mike-thinks:~/Programing/Rasa_tutorial/moodbot$ python3 -V
Python 3.5.2

And here the other attempts I try:

mike@mike-thinks:~/Programing/Rasa_tutorial/moodbot$ python -m pip3 install --upgrade pip
/usr/bin/python: No module named pip3
mike@mike-thinks:~/Programing/Rasa_tutorial/moodbot$ python3 -m pip3 install --upgrade pip
/usr/bin/python3: No module named pip3