Shin Splint – 2 weeks out

Good afternoon everyone,

I am two weeks out from my marathon. I have been following the L3 Marathon Training plan pretty much to a T throughout, with very, very minor deviations. I decided to be an absolute idiot 3 weeks ago and try a new shoe insert, which, after 3 runs, resulted in the most painful shin splint I have ever had (could even be a stress fracture). I alternated between an Assault Bike (it’s all I have) and runs, making sure I hit my long runs and interval runs, but using the bike for all my Z2 work. It is not improving unfortunately. I wanted to get some feedback on the next two weeks. I have my 3rd 20 miler on Saturday, then I start to taper. Should I just stick to the bike until I can run without pain (hoping that happens)? Or should I continue to manage what I can running and alternate back and forth.
To be clear, I am running the marathon no matter what, so postponing or finding a different one is out of the question.