Linear Niagra?

So today as I need to chop the hedge down 😳 I noticed some stretch marks that were not there last week and that dark line going down to my v area and a little on top of belly button too. It is mid to dark brown at the moment. I thought this happens late in pregnancy. I should be no more than 7 dpo. I didn't get mine last pregnancy till at least before the second scan. Can this happen even when not pregnant? I am yet to test as it is too soon to do so. I am freaking out now and hiding it from hubby until I know for sure.