MIght something be stressing him? Is there work being done nearby, a new dog moved in the neighborhood that barks a lot, couple in a house up the street fighting all the time?
I agree that all-day crating is concerning in an adult. Do you have room to set up an ex-pen somewhere? I think he needs time to break some of these new habits, then I would try gradually longer periods of unsupervised time, the same way you start a puppy,
It can also be a sign of boredom or separation anxiety. I did research before n actually saw that mental stimulation is more tiring than psysichal one. Stuff kongs or put his daily food in those food dispensing toy. It will make him eat slower, stimulate his mind and give him work to do. Training simple commands also help. Also there are matts where u can hide treats in, as an extra puzzle to solve. Corgis are intelligent and they need to be mentally stimulated