Method to determine 2nd Biopsy? + Strange "Other" symptoms

Hi,
47 yr, white male with father onset history of PCa at age 63. My recent PSA test showing 4.8 vs. the 2.4 level taken 10 months previously at my 1st PSA test, so velocity is scary. Subsequent, 2nd lab Free Vs Total PSA was taken and confirmed again the 4.8 total PSA and showed 11% free PSA. Urologist performed Biopsy (18 Truss Guided) with high yield samples IE> all usable samples at pathologist evaluation showing no cancer with a low grade PIN on one sample (urologist says this is nothing). My prostate volume is 40cc and pushing up into my bladder. I'm athletic 175Lbs. and 5'10" with minor symptoms over past 1-2 years prior . Post urination dribbling, sporadic painful ejaculating, 50% reduced ejaculate volume, but mostly minor issues and did not alarm me. In fact , 2nd PSA test was only done at MD physical, as I have had other serious but unexplained health concerns developing last year (Extreme fatigue, confirmed vision loss, heavy Joint aches, Stiff muscles, Light dizziness ongoing, increasing Memory loss...Remember, I'm very fit and I feel like something's big wrong ) GP says all test "other" so far are normal except PSA and that he tested for broad spectrum of issues including Thyroid, Autoimmune response, Rumitoid, ect.

After negative PCa biopsy MD has placed me on Avodart (dutasteride) for 6-8 weeks as "troubleshooting tool" with follow-up PSA test to determine if 2nd prostate biopsy is needed. He claims that PSA should reduce by approx. 50% after 6 weeks and if it remains high, then PCa is again highly suspected, hence the second biopsy ? Cannot find any literature on this concept.

Dutasteride links claim that it reduces PSA (undefined value) even in presents of PCa but times say 4-6 months for reaction time, so I'm getting confused about goal here. Any validation or feedback on this method and any comments of the other symptoms I noted Ie, could they be PCa related or other ? feedback is greatly appreciated.