If she's breastfeeding she's not constipated..there are some babies who will go once a week..my first son was like that and the dr said it's normal..as long as she's only breastfeed.
I believe it is 10 days with no bowel movement before you have to worry. There is a q-tip trick you can do but you never want to do it often because you can train them not to go without it. Just call your pediatrician. They will help sooth your worries.
As a former pediatric nurse I would say don't give her anything until you talk to her pediatric doctor. She's only a week old and you need to check in with them. How long had it been since her head had a bm? A few days for a breastfed baby is normal. Some natural things to try are a warm bath which helps relax the intestinal tract, rubbing her tummy in a clock wise motion- that helps stimulate the bowels. Also laying the baby on their back and pumping her legs in a bicycle like motion. Pediatric docs always want to see babies, especially newborns before they suggest anything. I'd give them a call.
Kayro syrup in a bottle of milk. You can do a little in a couple of bottles. It is about all you can do right now with her being so small.