Low blood pressure in teens. Required?

Hello doctor My daughter often panicks and takes tension  in school because if no air conditioner in school. She fears that she might get her  blood pressure low in school and then what will she do. Is there any home remedy to treat low bp in 14 years. She takes 7up.with her everyday with some salt so that whenever she gets herself with low bp she would add some salt in 7up and get normal. She  says it feels comfortable or not. I told doctor but he said it may be due to iron deficiency. After her menstruation her face becomes pale Plz tell me some home remedy or tips to treat this problem. And what diet should she take to solve this problem.. any medicine required??? Her only cause is tension how to cope with this