"Marshmallow Root" may help for prostatitis. There are many other herbs such as "Queen of the Meadow" that also may help. Everyone is different, so I suggest that the person that is having this problem try different herbal teas. The internet is a good source to learn more about this. Seeing a good doctor seems to be the right thing too.
Often herbs that are used to treat cancer are in the "unproven" therapy area. But, some people claim to have gotten well this way. I believe if they do, they have combined healthy eating with herbs together, along with no smoking or drinking alcholic beverages. They must put their body in the most perfect state to heal itself. It's rare that you hear that someone is healed this way. It takes a disciplined person to follow this healthy course.