Re: fluctuating PSA
A lot of prostatitis is not bacterial and won't respond well to antibiotics. Hopefully, you are not experiencing symptoms.
There are two tests available now that may help you decide if further explorations are warranted: % free PSA (a blood test) and PCA3 (a urine test following prostate massage). PHI, another blood test, will be available in the coming months.
Poking random holes may not find any cancer, if it is there. The standard 12 core transrectal ultrasound-guided (TRUS) biopsy only looks in one part of the prostate, the peripheral zone, where most prostate cancer occurs. However, there are several non-random methods available.
The "gold standard" is a transperineal, systematic template-mapped biopsy. This goes through the perineum rather than the rectum, and takes out about 30 cores from all areas of the prostate.
The other kinds of biopsy techniques involve image guidance to locate suspicious areas where biopsy cores are taken. There are two basic types, and they are highly specialized and not available everywhere. As you are in NY, you might want to check with Memorial Sloan Kettering. There may also be clinical trials in your area of some of the more advanced detection options.
Multiparametric (mp) MRI-guided biopsies may involve any of several kinds of MRIs (e.g., T2, DCE, DWI, MRIS). The best imaging is done with a 3 Tesla MRI and an endorectal coil in place.
Multiparametric UltraSound (US)-guided biopsies may involve any of several kinds of US (e.g., Color Doppler, Sheer Wave Elastography, Contrast-Enhanced). In the hands of experts, these can detect lesions about half the size of the best mpMRIs.
Some centers are now fusing the images from the US and MRI techniques to get the best of both worlds.
The problem with both the MRI and the US techniques is that they are highly dependent upon the experience of the image reader. It takes many years of practice to reliably detect lesions using these techniques. I know of only 3 doctors in the US who can accurately use color doppler US, for example. IMHO, it would be a waste of money to do any of these if the image reader does not have many years of experience at it, and because they are fairly recent, there aren't a lot of experienced readers. It's something to ask about if you choose to go with one of these.