Will a piercing get infected if you take it out after one week?

You can take it out but don't leave it out for too long because new piercings can close up pretty fast. Make sure that the new bar that you are putting in is clean and sterilized, otherwise it could infect your nipple and it really hurts (it happened to me). If you can't get the bar back in, make sure that you can get help from someone else or go back to the shop you got it done at and get them to assist you. And do it quickly, because as I said, if you've only had it for one week it can close really fast.