Hi,
Welcome along, as Adrian said its good that you are seeking help and advice on behalf of your dad.
The delay is difficult to cope with but it is what it is. If it was viewed as being urgent then it would be quicker, prostate cancer is slow growing so a few weeks here and there are not likely to cause a big difference in outcome.
As regards his pain, I can tell you from personal experience, the old brain kicks into overdrive and links every niggle into the possibility of PCa. It is more than likely that he has just strained himself, but that the possibility of having pca amplifies the feeling that he would have brushed off with paracetamol just a few weeks ago.
The told me my MRI showed that it was very likely to be PCa, so I went into a bit of a doom spiral before I got my biopsy results. These were completely clear so I'd spent a few weeks worrying for nothing.
The biopsy is the only way they can confirm one way or another if your dad has got PCa. Only when the results come back will you be able to see what needs doing. When one came back negative it still changed my life, my outlook on it and the way I look after myself and my family. So be prepared that if it's good news he will still have undergone some emotional change.
Keep on chatting here and gaining knowledge that will help you support your dad once the biopsy is done, whichever way it goes.
Take care and stay strong, it might not be asbad as you are thinking.
Mick x