Enlarged prostate is not caused primarily by ageing. (post-puberty that is) It`s just that age will usually correlate with the real cause, which is excessive DHT levels. This again leads to the symptoms of androgen excess like; BPH, male pattern baldness, acne, dandruff, excessive body hair, and also things like PCOS and endometriosis in women. (Many cancers will also be triggered by this dynamic in time)
The fundamental cause of all this is insulin resistance first of all, and also things like caffeine/methyl-xanthines. We are not as a species adapted to the modern industrial diet and lifestyle, and this can be said to be the cause of most of the diseases of civilization. You don`t observe these conditions in hunter-gatherer`s, which makes sense as they are not exposed to the monstrosity that is the modern industrial diet.
It`s obvious that if urinary/prostate symptoms comes on suddenly after starting PE, it has to be triggered by the exercises in some way. However, it might be that underlying BPH makes you more susceptible to those issues. It`s very easy to cure BPH! Fasting for 8 days will reduce the prostate with almost 50 percent. Eight Days of Water-Only Fasting Promotes Favorable Changes in the Functioning of the Urogenital System of Middle-Aged Healthy Men
But any diet that reduces carbs, (paleo-keto) fat (not recommended) or just total calories will do the job. Also then eliminating coffee/tea/dark chocolate if possible would be very helpful. I would aim for a more paleo-type diet and also do some fasting and see it that improves the symptoms. I think it most likely will have a positive effect.