Been there and got the tee shirt. Not run more than 5 miles since London Marathon 2005. Tried lots of Physio,- 2 years ago I had a Consultant look at it. I was told I had torn tendons off heel - they cannot re-attach without growing bone. I now have a large bone growth which is seriously sore. Xrays and scans, + steroid injuectons - no improvements - achilles feels as if it needs stretching 24/7 - no stretching works
I started using muscle rubs 6 months ago (theory being to improve blood flow to injured area). During the day I use the rub and wrap the heel in cling film!!!!. At night, just the rub to allow the foot to breath. RESULT
Tendon is no longer tight, I am running 5-6 miles (although after it still needs serious icing. Cannot run on consecutive days but aleast I am running. Sounds daft but it worked for me. Poundland has cheap muscle rubs that seen to work.
Seeing a pediatrist this week for gait analysis with a view to custom orthotics. - I will keep you posted.
Wish you luck,, but you may need to revise your training for long miles
STILL LIVING THE DREAM THOUGH