Hope this helps just a little.
I once had a fistula diagnosed at an emergency appointment with a doctor .... just a few days after my youngest daughter was born. I was 43 at the time and had been suffering with major rectum area pain - mostly when sitting down (on a pillow).
I had an old-fashioned emergency colonoscopy in the doctors office and he scheduled emergency surgery that day. I needed a spinal because of the very quick timing of the surgery.
Now the good news .............
That was 28-years ago - and I have had no symptoms or problems since with the fistula. It was also 18-years before I was diagnosed with PC.
Wishing you positive results.
Peace and wellness
Rob & Gizzy
Initial Dx of PCa in 2003/2004
Radiation (5x5wks) & Brachytherapy (96 seeds) in 2004
Low PSA for 6-years then Casodex briefly
Lupron from 2011 to current
Zytiga 2012 (5-months) - PSA increase
Prednisone & Xgeva from 2012
Taxotere - August 2012 (30-weeks) - PSA from 54+ to 12+
No chemo (8-wks) - PSA to over 23
Xtandi - June to Aug - 2013 - PSA increase
Jevtana + Lexapro - from October 2013