Advice?

Here is my two cents worth.

First off, heavy calcification can cause the PSA and fPSA to bounce all over the place due to constant agitation of the prostate. I had the same problem, but with me a biopsy did confirm cancer.

I would still ask for a round of antibiotics and maybe a week of anti-inflammatory drugs (naproxen, or ibuprofen) and then get a retest.

I had a 3T multiparametric MRI with and without contrast, and in my case, it didn't show anything. And from what I have read, for low grade, low yield prostate cancer it usually doesn't show any abnormalities.

Of course a biopsy is a shot into the dark and only targets a very limited area and with isolated cancer can be missed entirely.