How can I fix my pokemon white so I can tuck in a pokemon?

I live in America but I took a vacation in England. I took my DS with me so that I could play it when I wasn't doing anything, and so that the in game day synced up with the real day, I changed my DS's clock to match the time difference, and now, I can't tuck in a pokemon at all. It keeps saying to wait 1 day to tuck in a pokemon. How can I fix this? I want to be able to continue playing this game to it's fullest :(