How long will you live without knowing you have a brain tumor?

Not to worry. Not to worry too much in general. Brain tumors are rare compared with other tumors. The pain and swollen glands you list are not usually symptoms of a brain tumor. To answer the question, longevity depends on the type and location of tumor and what treatments are available.
Brain Tumor. It totally depends on the tumor. Some tumors are very aggressive and you only have days to weeks to live. Others are not aggressive and can be present for decades without causing death.