What Causes Testicular Pain?

Hello, i am 29yrs old having this sensational pain at my left testicle for 7months now. I feel better when I sleep and wake up but the intensity of d pain increases when sitting especially for a long time. This testicular pain I believe resulted to me having waist pain because the waist pain reduces when d testicular pain reduces. No medical examination has been carried out so far. Please, kindly assist me in what could possibly be the cause and treatment, thanks