picking nose until it bleeds- help!

i'm seriously at a loss of what to do. my almost 6 year old step daughter picks her nose so hard it bleeds badly. we have her on the weekends and it happens here about once a month and we tell her she needs to stop picking it and use a tissue if there's something in there. we've had here all spring break and it's day 5 and it's the second time it's happened and this time it was gushing blood it literally was making me sick and then she sits there and cries because there's blood coming out. it's a huge mess and an unhealthy habit and Idk how to get her to stop. please help 😣😣