I made a new conda environment with clean installs of just the packages I needed and started getting a different error when importing pymc3 or theano (something about lazylinker missing). I tracked it down to this stackoverflow thread and the mingw that came with git was conflicting apparently. Removing it from the path seems to have solved all the issues.
As for how/why this was running just one day ago I am willing to chalk that up to Windows being Windows