Like so many others, I've run into this same problem. I installed 2 mods from Skyrim Nexus (Warzone Civil Unrest, and the faction armor pack that go with it) and 2 Steamcommunity mods (Wolf Pack followers and Convenient Horses). I've deactivated, deleted and re-activated the mods, and went back to before any of them could have taken effect. It only affects one of my characters, but it affect him on every save file (he's a Dark Elf if that's any help). It can't be the food glitch because I only use potions, never food. Fortunately, I have a good number of spells, but absolutely no shouts set to my favorites. I didn't notice the problem until I went to Windhelm and wanted to use Clear Skies. I was in Whiterun the day before.