What Causes Frequent Urination And PSA Level Of 2?

Question: I am a 68 year old male in very good health--exercise regularly, never smoked, not overweight, very active. I have been experiencing sporadically frequent urination for over 10 years. My PSA has never been above 2. My urologist says my DRE shows a normal prostate. I have been taking Myrebrtriq for 2 months, and it seems to help at night (I get up to urinate every 3-4 hours at night, so only 1-2 times per night). However, during the day, I sometimes have to urinate every 30 minutes, and the drug is expensive ($75 per month with insurance). No pain and usually a good stream (unless I hold it in too long). The only thing that helps consistently is Advil. If I take 1-2 Advil, my system slows down, and my frequency reduces to needing to urinate only every 3 hours or so. Once the Advil wears off, I generally have to go about every 2 hours or so, but now with the same urge or frequency. My GFR for my kidneys is slightly low, but a few years ago, I had a complete kidney study and everything seemed fine. Exercise, especially anything that stresses my lower back like sit-ups, seems to start up the problem...until I take an Advil. One doctor told me Advil, while it does have some disadvantages, is less potentially a problem than other drugs, as long as I don't take more than 8 per day (which I never do). So...any suggestions for what I should do/try next? Anything here that I should be worried about or have checked further? Thank you.

Thank you, Dr. XXXXXXX In answer to your questions:
1) No, I am not diabetic.
2) Yes, I do have sporadic urgency--this seems to vary; for example, it is worse in allergy season, and it seems worse after eating certain foods (spices) and drinking certain beverages (red wine), so I tend to avoid them. However, again, Advil seems to control the urgency when it occurs.
3) Urine stream varies--generally fairly strong, but if I have held it in for a long time, it tends to be slow.
4) Yes, I have had ultrasound, and my prostate is slightly enlarged but two different doctors have said it is not overly large based on my age. The ultrasound shows my bladder adequately empties after urinating; however, sometimes the bladder does fill up again (within an hour), necessitating another visit to the restroom.

One doctor has speculated that the Advil provide an anti-inflammatory effect, which relaxes my bladder and surrounding nerves and muscles. Given the fact that my triggers for frequent urination seem to be tension or irritation apparently caused by muscle aggravation or allergies, the Advil effect might make sense. Does it make sense to you? Another question for you: How would I know if this is something more serious than OAB? I sometimes worry that perhaps I have a serious prostate problem that is somehow being missed despite the digital exams and the low PSA. However, I want to avoid a biopsy unless it is deemed absolutely necessary. Please give me your guidance on this. Thank you.