My baby has a weird knot on her head...?

Judah uterus 7mos old and I just noticed this knot thing on her head. It's weird cuz there's no bruising or anything and you cant see it, only feel it....it starts like just below her soft spot and runs down her fore head. You can feel it but not see it at all. Her head looks completely normal and she hasnt been acting different or anything and it's not bothering her. What the heck could it be??