Today I got the results from my MRI and it turns out that I have a tear in my Achilles tendon. This explains a lot. I've still been in a ton of pain, so my doctor has me wearing a walking boot. While wearing a boot is not the highlight of my day, I am excited because I think the boot will get me on the road to recovery. I'll have to wear the boot for 3 weeks, then after that hopefully I'll be in better shape. I'll keep you posted.
One thing I will say is this: wearing the boot is not comfortable, and I notice that I have to put a lot more thought into doing the normal, everyday things in my life (walking, thinking about where I park, etc). I do think that things will get much easier once I get the hang of "boot walking"though. We'll see.