Thanls for your post Helizabug, I do not think that I am de hydrated as I am drinking a lot throughout the day. I was advised before the operation to drink at least 8 glasses of water, on top of tea and coffèe
I feel fine during the day, but during the night I seem to become hot (Although I do not have a temperature), have a very dry mouth, lips and eyes and end up taking paracetamol because of having a head ache. Not quite so many visits to the loo now, so I think that things may be improving.
I seem to remember that I had similar issues after a hip operation in 2012 and probably after my last knee op so I am hoping that things will settle down soon.