I havent read all the posts on this thread, so I am not sure if anyone else has mentioned this... but - its worth thinking about how other niggles and parts of the body all fit together in the bigger picture.
I lost most of last winter to achilles tendonitis. I was injury free for about 4 years and I hit big mileage. But then last winter I had knee niggles, a calf pull and then achilles tendonitis that would not go away. I would rest, then it would come back as soon as I started very short runs again. I had a great physio and we traced it all back to my lower back. It had got all locked up so I had reduced mobility on my left side - the different strengths between my sides was noticeable. As soon as we got it unlocked, I was able to stretch effectively, and can keep the achilles tendonitis away (and all the other niggles too!). I now do a whole load of work with my back and core to stop it locking again, but can recognise when it starts so that I can stop it.
If you keep getting recurrent achilles tendonitis, it might be worth investigating if it is a symptom of something else.