Actually Tenosynovitis (inflammation of the sheath) but AP doesn't have that as an option. This is an old injury - from the late 1980s that flares up from time to time.
See log - started to hurt at 4km, significant pain at 5km during 8km run.
Could not use normal walking action today without severe pain. Have iced it several times, will probably need a few (4-6) weeks off running, and if pain is still bad tomorrow will consult Duncan.
Still have injury, severity has decreased enough to enable running thanks to Alfedson's exercise (heel raising and loweing). No doubt it will come back to trouble me again.