I have a family history of cancer and i have had a painless swollen lymphnode on the left side of neck along with night sweats. what could it be?

Get it checked: An enlarged lymph node and night sweats could be sign of a lymphoma, such as Hodgkin's, which is a very treatable form of lymph cancer. On the other hand, many people have benign small lymph nodes related to a recent virus, sore throat, etc. See your doctor to get it checked out.

Anything: You need to have a doctor take a good history and do a full examination. If necessary, he/she will order scans and or a biopsy. It would be premature to start making guesses about your problem. Could be anything, infectious, inflammatory, or yes, even cancer. Best to you.