Praying for healing for your father and prompt and accurate medical care if there is some tissue damage or joint displacement that can be easily fixed. Perhaps an xray would help with a medical exam to ensure there is nothing more serious, but seek an MD or DO health professional and take no advice from the internet on stuff like this. An in person exam is essential and you can get all kinds of terrifying ideas from trying to be your own MD.
I pray for healing for your dad, I did a similar thing this week and have been taking Ibroprufin and paracetamol for the last few days. A hot bag helped to ease the pain and I had a good sleep this morning. At last it has gone and I can stop the tablets. I can pray for your dad knowing what he is going through.
May the Lord bless him and bring relief from the pain in Jesus name.
I agree with someone above who said that heat helped relieve pain. Turmeric with black pepper, which is sold in capsules, has helped many with pain. Also white willow.
Another thing that can help is a liniment made with something like olive oil, with myrrh and frankincense essential oils.
I pray that the Lord will lead him to whatever causes healing and relief from pain.