So I've worn an 8.5 since like middle school. Tuesday, I had my shoes on and by the end of the day, my feet were absolutely killing me, but I assumed they were swollen or whatever. I worked from home Wednesday, and then Thursday, I went to put on a pair of slip-ons that were also 8.5 and my toes were smashed in the end. I had a pair of 9s in my car that were there to take back because they were too big...i am wearing those now. And they fit. I'm apparently a 9 now. It happened like instantly!!