A 22 year old sexually active male came with 2days history of fever with pain in scrotal area. Examination: scrotal skin is red and tender. What is the most appropriate diagnosis?

The key is D. Epididymo-orchitis. [In epididymo-orchitis there should be fever, elevation of testes reduces pain (positive prehn sign), In torsion testis lies at a higher level. In torsion urinalysis negative but in epididymo-orchitis it is positive. Epididymo-orchitis usually occurs in sexually active man].