Wow, I have never heard of taper madness before, but its funny how everyone can probably relate. I am by no means an expert on running injuries, but I thought pain that eased with usage was more indicative of muscle pulls. This would also be consistent with relief felt after icing, I guess the same could be said for tendonitis. My question would be, after you noticed the pain, do you think you altered your stride subconsciously to provide relief while you ran? If so, do you still run with a somewhat different stride? You mentioned that you walked a steep downhill, that would be a situation where you most likely to run differently that you otherwise would. I think Taper Madness makes a lot of sense and I think it would hold that you would be more likely to run differently at the first sign of any discomfort. I could be way off though.