I fought that diagnosis for quite some time and even managed a bit of running here and there until I finally gave in and got x-rayed. At first we didn't see the bit of fuzziness that indicated the fracture. About two weeks later (with a run or two thrown in - and some bike riding) when things weren't getting any better I went in to see a Sports Medicine doctor. He diagnosed the stress fracture based on exam and another look at the x-rays.
So, I now have an air cast/splint and strict instructions to do nothing running related for two weeks. Biking is okay because:
I do not use clipless pedals (so no twisting of the lower leg) and the trails are too muddy for single-track mountain biking, so I will not be riding any technical trails with a chance of falling/needing to get my foot down in a hurry.
The funny thing is my leg is almost too short for the cast so biking is a bit uncomfortable anyway.
The Spring Superior races are off my schedule. I am being allowed my annual spring trip to Isle Royale because it is 3 weeks away and our intent was to base camp anyway. I will not be running the trails out there as originally planned and was told I had to be "very leisurely". Backpacking is out. Lucky for me it is a perfect time for spring wildflowers and now I have a perfect excuse to dawdle along identifying plants and taking lots of photos.
He seems to think I can be back at it in time for Voyageur - if I behave myself, but no PR's ;->
I am already looking at the calendar and thinking that may - or may not - be reasonable. There is always Wild Duluth 100k to look forward to in October though!
On the bright side, not being able to run for the past 7+ weeks did teach me that I can bike in temps down into the 20's in relative comfort (stole a pair of Mr. Wildknits winter gloves).
My knitting is also getting more attention. I finished the toe socks and promptly cast on another pair of socks, this time using a Nancy Bush pattern from Folks Socks. But right now I am very involved in knitting up a 'secret project'.