I am not sure that this would be tremendously helpful, but I have experienced two infections and one really bad pain since having my biopsy and my radical retropubic prostatectomy in December 05.
The first was a prostate infection from the biopsy. Had antibiotics to clear that up.
The second was a pain that seemed to be coming from the perineum, like someone shoved a burning rod into my body between the rectum and the scrotum. This, from a urinalysis, turned out to be a bladder infection after the prostatectomy. More antibiotics for that.
The third pain I had was in my scrotum - I thought it was the testes. I thought I had testicular cancer as well as the PCa. I went for an ultrasound of the testes and my pain turned out to be caused by varicoceles. Lots of pain but no fever associated with it. Still, I find that the pain at times is debilitating - sometimes just steady throbs. I need to get the celes dealt with but haven't yet since my prostatectomy was followed up with EBRT radiation sessions in 06. My urologist said let's deal with the more important PCa treatments, then do the varicoceles later in 07.
Since your father is a retired physician he probably has already ruled out varicoceles, but an ultrasound of the testes might show something.
Just an idea! Hope he finds out soon what is causing the problem.