Achilles Tendonitis: Inflammation of the Achilles tendon, connecting the calf muscle on the heel bone, usually a result of overuse. This leads to pain and stiffness within the back from the heel, In particular for the duration of action. While NSAIDs might ease indicators, they don't deal with the foundation https://www.theorthopaedicandpainpractice.com/why-does-the-back-of-my-heel-hurt/