Mayor Thomas M. Menino will remain hospitalized indefinitely while doctors continue to perform tests to determine the source of the most recent pain in his back, the mayor’s spokeswoman said Friday.

Menino has been at Brigham and Women’s Hospital for three weeks with a variety of ailments that have included an upper respiratory infection and a blood clot that traveled from his leg to his lungs. While hospitalized, he suffered a compression fraction in one of the vertebra in his spine.