I have a uti and got bactrim (sulfamethoxazole and trimethoprim) today to treat it but im having pain on a lump on the back of my head. i'm curious to if its a lymph node and if its norm?

Maybe (not) . . .: Urinary tract infections do not cause swollen lymph nodes, especially not so distant as the back of one's head. While this lump could represent a lymph node, it could also be an infected cyst or folliculitis. Since it's painful, please go see your Family Doc for evaluation & appropriate treatment. In the meantime, finish your antibiotics.