Thanks Barry. He has had gout ruled out by a blood test.
He had an MRI and ultrasound and one of them (I can't remember which) showed bone erosion.
For me the strange thing is how the foot turns a different colour as you can pretty much see the blood flow into the foot. It's very strange.
It has been mentioned that this is because he is 74.... And just one of those things.... A mere coincidence that this has started and he just happens to have started cancer treatment.
He is managing to limp round the golf course so that's a positive!