Pain in Sexual organ and zero flow.

Hi , I am having sexual issues past 6 month . I used to do masturbation for almost 6 years . I never had such issues . Recently l found my prostates enlarges, apart from that l used to have a pain in my left side while l do masturbation . And now l realised my urine flow is Low and also the flow of sperm and fluid too Low . I seen gastrologist , medicine & urologist and no body advised me anything . They are not able to find the reason of pain in my left lower abdominal part . I also feel inflammation in my urinary part and feeling itching in my inside of penis . I need a advice for the treatment for such issues . Which doctor should l see ? What is the reason behind my pain in left side while l do masturbation ? What is the reason behind zero flow of sperm & fluid ?