I had 8 urinary tract infections in 2013. i have another one but it came back negative. what else could it be?

UTI: Without knowing the details of your illnesses it is difficult to predict what this may be, but if you have actually had this many utis you should definitely be seen and evaluated by an infectious diseases expert or a urologist or both. You will require detailed history and undergo physical exam and testing. Bring all your medical records including labs with you and prepare a written history.