How Do You Know If You Have Prostatitis?
(This information is from Dr. Patrick Walsh's Guide to Surviving Prostate Cancer)

As described previously, acute bacterial prostatitis leaves little room for guesswork. Other forms of prostatitis, however, cause milder symptoms (and asymptomatic inflammatory prostatitis doesn't cause any symptoms at all) that may not immediately suggest that the prostate is to blame. The constellation of symptoms of prostatitis includes pain in the perineum (the area between the rectum and testicles), testicles, the tip of the penis, the lower legs and back, and during or after ejaculation, as well as blood in the urine, the need to urinate frequently, and incomplete emptying of the bladder.

You are at higher risk of developing prostatitis if you recently have had a urinary catheter or other medical instrument inserted into your penis; engaged in rectal intercourse or oral sex; have had a recent bladder infection; or have other urinary problems, including BPH or an abnormal urinary tract. Stress also seems to play a role in prostatitis. (Note: If you have undergone recent surgery or any other surgical procedure, be sure to tell your doctor.)