What would my pediatrician do since my period has been longer then it should be and my breasts are sore? is it necessary to undress completely?process

Depends: It definitely depends on how long you have been bleeding and what your sexual history is. Breast tenderness is often associated with menstruation. When you go in for an evaluation a pelvic exam may or may not be warranted. Likely your doctor will want to do a urinalysis, urine pregnancy test and ask questions about your menstrual history.