Have you had anyone look at your running technique or double under technique?
Technique with these skills may be an impacting factor.
Have you tried any of these?
Free Your Heel, Free Your Mind
Episode 25: Heel Cords of a Cheetah, Achilles Well Being
Episode 115: Lower Leg Sliding Surfaces
Episode 167: Unglue That Heel Cord
Episode 237: Heel Cord Love
Episode 319: Protect Those Heel Cords Man!
Episode 337: Long Ruck Feet Or Ultra Marathon Feet?
Episode 350: Tack And Floss: Heel Cord Edition