help please

I recently posted a request for help with Flukes and would like to thank all
those that helped me out - the problem is gone - I think. However, on
waking up this morning I found I have a one year old koi doing spirals in
the centre of my pond. He seems to be bent slightly sideways and just
swimming round in tight circles. I can't see any signs of anything
physically wrong.
Any ideas please.
TIA