Hello, It is very difficult to point at sexually transmitted disease (STD) based on this presentation alone. You should visit a general surgeon. He will examine the infection as well as examine the testicular lump. He will order a culture and sensitivity test on the sample collected from the infected cyst and should start your son on a broad-spectrum antibiotic until the culture results are out. The lump could be something as harmless as a hydrocele or epididymal-orchitis. It need not be an STD because it is occurring in a sexual organ. Any idea for how many days is he having this sore throat? Are you seeing any whitish patches inside in the mouth or in the throat? When you are visiting a surgeon, you can discuss it also. I do not see a direct correlation between these three at this point in time. Further lab tests, including a peripheral blood examination, and a clinical examination by a surgeon should be your first step now. Hope I have answered your query. Let me know if I can assist you further. Regards, Dr. Sabarivel Janarthanan