Can stress and holding tension in your pelvis develop into a certain form of prostatitis?

No: Never heard of those factors being the cause of prostatitis. In most case, there is some sort of infection that triggers the process. Yet, it often continues even when the infection is gone evolving into chronic prostatitis. Stress may contribute to some urinary problems such as urgency, discomfort/pain but would not be the cause of prostatitis.