Hi Lisa. You are doing the best thing for your dad--being there for him when he needs you. My daughter has been wonderfully supportive during my own prostate cancer journey.
I'm not up on prostate cancer recurrence therapies, but it sounds as if the negative scans give plenty of hope to beat it. I have read in prostate cancer books that chemotherapy is not effective for prostate cancer, but don't quote me on that. I would suggest that you not hesitate to get 2nd opinions, if needed.
Please come to this forum to read and post as you need to. There's a lot of experience, strength and hope here that you can borrow any time you need it. Take care and hang in there, Lisa!
Age 58 PSA 2.6 Gleason 5