I didn't mean for you to run those commands immediately, just to check whether you have been installing Python packages outside of yum (which causes conflicts).
Regarding this issue, I believe this could help:
yum -y reinstall python2-acme certbot
But if not, you might try giving certbot-auto a go. It's hard to know what state your Python packages are in, but certbot-auto runs in a way that isolates its dependencies and should work around any issues that you are having.