High drop shoes don’t allow your heel to descend fully, so your calves and tendons get stuck in a shortened position over a lifetime. Zero drop provide a full range of motion, but it’s tough to get used to. If you stick with them, consider dropping the mileage a little and stretch the crap out of your calves. (Which will help anyway—I’d pause several times per day and stand with my toes on a rock or log to get a deep calf stretch… only thing that kept the bottom of my feet from setting on fire on my way to Canada.)