So i think someone is wrong with my relative?

my cousin is in her 20's and she said lately she has been feeling very sad for some reason but she doesn't kno why. she has no appetitie. she takes meds for something but i dont know. i think it might be depression. but she said she never really had a good time in highschool, and so i think that might have an effect on her. she is not doing very well in school, and she feels as though all of her friends are getting at her. she feels like people are constantly talking about her, and she gets paranoid about the littlest things.. like when people glance at her she thinks they automatically dislike her. what should she do? ive been trying to help her and reassure her that things are alright, but honestly im not sure. should she go see a therapist? is this serious ? what should I do to help her? im really worried about her, and don't want her doing anything she regrets.