Hello. I m sorry you don t feel well. Although having multiple sexual partners increases your risk for serious infections (HIV among them), and while a STI is certainly a possibility here, there are a number of other conditions that could cause your swollen lymph nodes, headache, night sweats and fatigue: tuberculosis, lupus, rheumatoid arthritis, toxoplasmosis, Lyme disease, infectious mononucleosis, leukemia and lymphoma are among the many possible causes. Given your history, you should be screened for STIs, in particular HIV. If you re HIV-negative and you don t have any other STIs, further investigation is warranted to identify the cause of your symptoms and determine the best treatment. Good luck!