Will a doctor still do a rectal exam if im on my period?

Depends: Most doctors who do a rectal exam use a separate glove than the one they use for their vaginal exam so as not to transport possible viruses or bacteria between them. I don't typically perform routine rectal exams on women your age unless clinically indicated. Your period has no effect, however, on the exam, unless, of course, he/she is doing a stool guiac and is checking for blood.