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The symptoms could be suggestive of pregnancy, PID, pelvic adhesions, endometriosis etc. Wait and watch for her periods. Look out for development of any other new symptoms. If pregnancy is suspected, or if periods are abnormal, she should consider visiting her gynecologist for thorough examination (to confirm pregnancy related changes/signs in body) and blood/serum HCG level test (to confirm/rule out pregnancy accurately).
Take care.