Hi My Daughter Is 12 She Fainted 3 Times But

Hi my daughter is 12 she fainted 3 times but didn't loose conscious I did an eco and blood work and all came good I have been told it's a low blood pressure and I should add more salt she fainted again last night but she only dose that when she is out door and when it's humit and high temperature people are saying to check if she has stomach worms is that true and wat else I should be doing