Injured just weeks before my first marathon

I’ve been training for my first marathon in Philly and during week 14 of my 18 week training plan I started getting IT band pain. I haven’t been unable to run more than 2 miles due got the pain. I’ve been resting, stretching, and strengthening that knee ever since. Now, the marathon is 10 days away and the odds of me running this is slim. I plan on doing a test run a couple days before to see how it feels. Anyone have any other advice or similar stories for motivation? Do I hold off for a spring race?