Replying to What has happened to my boots?

So i got Full Tilt Classics last year. I got them heated and everything, and wore them all season last year. I just got back from a 5 day trip to PC and they were fine the entire time. Now on our way back (To CT) we missed our connection in Atlanta so all our checked bag (with my boots) just chilled at the airport all night. And when we get back home i decide to go hit my rail in my backyard and my boots felt a lot bigger and roomier than they ever have. Along with after an hour and a half the outside of my feet were considerably sore. So anyone know how/ why this happened?

Spark Notes- My boot fit fine before (for like a year). They were left in a bag in Atlanta for a night. Now they feel bigger and hurt.