So I have been slowly transitioning to full barefoot after a season of long sandal runs still resulted in some knee pain. Went slow with about 3 x 1.5 mile run per week was going great! last week ramped up to 7x 1.5m runs in 9 days, and noticed that I rubbed away a portion of my heel. the injury appears to be frictional in nature not impact. It also appears to have a directionality from back to front of foot with a fraying aspect on the leading/forward border of the injury. This did grind down to healthy vasculated tissue that did become painful, but I didn't not experience pain while running. Both feet have the same injury, slightly more deep on the right vs left. Right knee is my problem knee. I have included two pictures. Any help appreciated. I can't express how much I love running barefoot. Thanks in advance for any help!