Boots maybe too small
Last year I was riding in my local venue, VA obviously, and had no issues with set up (same board, boots, and bindings for 3-4 years) and everything seemed great! That was until I ventured up to Alaska to visit some friends that live there. I quickly found out that my boots were TOO small.
While in VA, shorter icy runs, I had no foot fatigue. While in AK, Loooong steep runs in pow, I could barely get half way down the mountain with out cramping my feet and calves.
Try getting fit for new boots to see if your foot size has increased. I did this and found I grew a half a size. New boots have helped my foot from cramping up.