Turns out it wasn't a stress fracture after all.
After a few days of wondering and thinking the worst, I couldn't stand it anymore so I went to a sports med doc. Luckily I got a physician who is a runner, and therefore sympathetic to runners. She spent lots of time asking questions and poking and prodding my feet. Then, she brought in another physician who did the same. He said that he was "reaching into the very bottom of his bag of tricks" but he thinks that somehow I got a broken blood vessel. That would explain the bruising and pain. A lot of the symptoms were similar to a stress fracture, but in my heart I just KNEW that I couldn't have a stress fracture. I have slowly and safely built up my mileage, I take rest days, cross train, and have a healthy diet. But I let negative thoughts and Google searches take over. I was convinced that I wouldn't be running the Phoenix Marathon, or even running at all for a few weeks.
The sports med docs suggested that I go for a test run and call them if there was any pain to schedule an MRI. It's amazing what some ice, elevation, and rest can do for an injury. I ran the happiest 4 miles of my life that night...PAIN FREE!
I learned a few things from this little experience.
1) Running is pretty important to me. I always knew I liked it, but when I thought I couldn't run I can't believe how devastated I was. This could be a good thing or a bad thing.
2) Don't believe everything you read on the Internet. Everyone has a running blog with their own story. Just because it happened to another runner doesn't mean it's going to happen to you the exact same way.
3) Hope for the best. When the podiatrist told me, "it could be a stress fracture...or a broken blood vessel", I only focused on the part about the stress fracture. I should have instead treated it like a broken blood vessel from the beginning. If that didn't heal, then I should have started considering a stress fracture.
I can't believe how grateful I am to be able to run 26.2 miles this week!