As part of an after-school fitness program, a 10-year-old boy has been running four days a week for the past three weeks. he is now complaining of unilateral, intermittent, posterior heel pain that presents while running, but improves with rest. upon examination, the athletic trainer notes point tenderness just anterior to the insertion of the achilles tendon along the posterior border of the calcaneus, pain with standing on the tiptoes, and a positive squeeze test. what condition should be suspected?