My one week old, formula fed baby has been having a hard time pooping. When she needs to go she gets fussy and cries. At first it was fine she would go every time after she ate, than about two days ago she only went once a day. Two days ago her poop over flowed her diaper and got all over. Now I been trying to help her poop so when she get fussy I stick a q tip with petroleum jelly on the tip and insert it to her butthole just the tip of it than poop comes out, but its not hard its like watery and loose stools. So I don't know what to do and what it is.

For starters I'd stop sticking things into her "butt hole" before you speak to her Pediatrician. Have you brought this to the attention of her Pediatrician? What has he/she advised?

She's only 7 days old - you don't have any idea what her schedule is or will be.

Here's an entire site about baby "poop." http://www.babycenter.com/baby-poop-101

OMG, STOP sticking things in her "butthole." It's called rectum by the way. You can cause some very serious damage that way.