How do you know you got lices?

i got a sew-in about a week ago and saturday night . i spent the night over my cousin(male) house and lye on his pillow . and that's when mt head started itching and sunday night it itched really bad , its been itching for three days now . how do i know if i got head lice or not . P.S without having to cut-out my sew-in .