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
, 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.