Anything with codeine in it makes me very sick...not immediately but after a few doses...so he may still not want anything after he wakes up.
If you want to test it out, stop the co-codamol, see if the nausea stops then re-start it and see if it returns.
As an aside I have also been prescribed tramodol for post-operative pain and I will never put that stuff inside my body ever again.....hallucinations, twitches, insomnia...dreadful stuff. I stick to ibuprofen and paracetamol now when I need pain relief. (and a hot water bottle or equivalent.)
I do hope his back and calf improve soon.