it could also be a relative mild case of plantar fasciitis.

i woke up one morning a few years ago, and went to put my feet down on the floor and the pain was excruciating. i couldnt walk. both feet at once. i never had had that pain before. it is in the arch area. after a while i could put my feet on the floor though painfully and hobble around with crutches. had no idea what was going on. one foot released itself going down the stairs. the other foot i needed a steroid injection. it never happened again.