About 2 weeks before my period i have extreme anxiety, heart races alot, & i get sad. it feels like it lasts long.feels better when i finally start.help?

Maybe PMDD: If the anxiety and depression predictably precede your period and go away after, you may (depending on how severe the symptoms are) have what is called "premenstrual dysphoric disorder" (pmdd). A number of treatments can help. A good first step would be a talk with your doctor.

Needs evaluation: The premenstral phase can be characterized by emotional symptoms as well as physical symptoms. A physician can assess your specific concerns and recommend treatment accordingly.