Well, considering that you increased your volume by 100% and added some
intensity, I would bet that you are on the right track as to the problem.
Another one could be that the downhills are causing extra pain.
The sprinting uphill might not be a problem is you're not overstriding or
moving upand and down (vertically) with your entire body.
In health and on the run,
Maintainer - rec.running FAQ
Director, San Diego Marathon Clinic, est. 1975
(Mindful Running) http://www.mindfulness.com