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Bleeding after intercourse can also suggest PID (pelvic inflammatory disease) or any cervical problem.
Since your periods are also delayed, do not ignore it anymore. Visit your gynecologist/healthcare provider to see if it is due to pregnancy or cervical problems or PID. If any infectious cause is found, then get your partner also treated simultaneously, and avoid having unprotected intercourse during treatment to prevent chances of re-infection.
Take care.