Is a weak urine stream very serious? should i see a doctor?

Weak stream: Weak stream is never normal, even if not accompanied by any other symptom [like burning + frequency + fever + flank pain]. It should never occur as a single symptom in young people. In older men, 50yo above, it can be simply bigger prostate then normal [and always also harder instead of being really really soft and not squeezing onto the ureter].