GarageGymsHeros makes some great points.
Have you changed the type of shoe you are running in?
Going to a flatter sole shoe or making changes in running technique have an impact too.
Rebuilding Your Feet With Brian MacKenzie
Rebuilding The Feet, Part 2
Rebuilding the feet, part 3
A couple for the achillies
Pro Episode # 57 – Managing Achilles “Tendonitis”
Episode 25: Heel Cords of a Cheetah, Achilles Well Being
Episode 319: Protect Those Heel Cords Man!
Episode 167: Unglue That Heel Cord
Start with some running drills and looking at run technique before just going out and running.
Build things back in with proper technique makes a difference.