Doctors Scratching Their Heads. Ideas

I insisted on a biopsy in September of 2015 after a couple of elevated PSA tests. (6.4 followed by 5.4). To the surprise of my urologist, one of six samples came back with 2mm of positive tissue. It was graded a Gleason score of 3+4=7. A routine post diagnosis pelvic CAT scan was performed to check for any signed of lymphatic change that might be indicative of metastisis. No signs were found but a 1cm leasion of some sort was noted in my L2 vertebrae. This was already known to me as it was detected 5 years ago in an MRI for lower back pain I was experiencing from bulging disks. That not withstanding, in October 2015, a bone scan was ordered which came back positive for potential leasioms on various ribs and my left shoulder blade. (The L2 leasion showed no additional uptake.) 

i had already selected and scheduled CyberKnife radiotherapy. The Neuclear Oncologist read the bone scan report and reviewed the images and thought the radiologist had over read the scan. I went forward with the radio therapy which was completed on the 20th of Nobember 2015.  Because of the positive bone scan, a Flourine PET/CAT scan was scheduled and performed on the day before my last day of radiation. The PET scan went from my head down to about mid thigh. The results identified the same potential leasions plus additional areas of concern. All areas of concern were located in bone. This prompted conventional X-ray studies of the suspect areas that demonstrated no signs of any bone changes indicative of bone mets. The X-rays showed nothing. As a result, no one wanted to do a CAT scared guided needle biopsy and a surgeon declined to do an open bone biopsy feeling that there wasn't enough there to find by blindly taking rib sample(s). As a result, to date, doctors have delinded  treat me for PCa bone mets. This is most understandable since my PSA has continued to decline since the radiation therapy and is 1.41 as of this day.  The Drs want a definitive diagnosis before treating me  

Since the initial bone scan and PET scan, I have had another of each scan. Both show the same results but for the most part, the areas of concern remain unchanged.  However, in the last PET scan, which was from head to toe, a very intense location of update was noted at the lower most location on my right tibia.  Before the scan results came back I started having a little pain in that location which I discounted as the likely result of me bumping my ankle on something in the middle of the night during one of my many trips to the bathroom. However, the pain has gradually worsened and become more persistent. After I saw the radiology report for the last PET scan, I had X-rays done of my ankle which the radiologist read as a small area of possible new bone growth at that very spot. 

I am hopeful that I can now persuade someone to biopsy this location and give me an answer as to why I have positive scans despite an increasingly low PSA. We have already ruled out multiple myeloma. Likewise, since the scans are essentially unchanged over a 3 month period, it is unlikely that I have the rare small cell low PSA producing variant of PCa Bone mets. That type of PCa is hyper aggressive and kills in about 12 months  

At this point I'm receiving no treatment. The doctors are all scratching their heads. Most don't believe it is PCa bone mets. The Oncologist says it looks like it from the scans but won't say for sure.

Any ideas? I'm very frustrated and depressed by all this uncertainty.