Never found the specific cause, there were too many suspects.
If I could back and time and change five things it would be to:
1) Take a day off immediately and do an internet search to read the large number of informative articles on the causes, treatments, and exercises regarding the various types of shin splints. It's not just one thing, but a few, with each being different. Find your type and get fanatical about the remedies till they work.
2) Do an intense pool running workout one, two or three days per week to help keep fitness, so any week has enough workouts to improve your fitness, or stay the same, never losing fitness, even if you back off running for a few days.
3) Forget the idea that you can tough out shin splints. Anyone can for a while, but it's a loser's game, as ignoring the pain, or gutting out the run ends a few months later with every runner who knows you telling you how tough you are, but you are no longer able to run, or walk without intense pain. You then are left with being tough trying to stand, or walk up stairs. It looks very pathetic and is.
4) Do the appropriate strengthening and/or flexability exercises before and/or after each run, or instead of the run, if you are less than three days away from pain from running.
5) Not running heals faster than any other method, but it can't be your only approach, as the eventual return to running will bring on the pain again. You have to follow steps 1-4 to improve as a runner over the long term.
Good Luck