What tests are available

Hello, Here's my symtomes since more than one year now. - Very low urinary stream - Constant need to urinate - Urine flow stops and proceed many times during miction - Need to exercise pressure on my abodomen so that urine flow goes on, even if my bladder is full - Low back ache - Vertical back ache - different ache in different part of my body, mainly elbows and legs - Irritated bowel syndrom from time to time All tests were made (in and out of hospital) but no doctor is able to determine the problem: no infection. Some says: - Over Active Bladder - Prostatitis No medication solved my troubles. Ditropan made some positive effect for around 2 weeks then all my urinary troubles got to a high level again. I need to check again if I have any type of infection. What ultimate test can I go for to determine once and for all if I have an infection. What would you advise about my situation? Thank you