I Am Concerned About My Daughter's Health. She Is 20

I am concerned about my daughter's health. She is 20 yrs. old ,her weight has dramatically dropped within the past 2 months she lost 10 lbs. she is 5.9 " tall and weighs like 100 lbs. she said she's been having pain in her hip. like a squeezing sensation and numbness. what could cause such rapid weight loss? she was just healthy 2 months ago. this is not normal for her. please advise.