Swollen hands and feet?

Since the TAH four months ago, but mostly the past month or so I've noticed that my hands and feet get swollen, more throughout the day and are better when I wake up, though my feet never go down entirely.

It's the sort of thing I would get after a really hot day and walking a lot or if I've been drinking alcohol (which I hardly ever do).

Is anyone else getting this and what could it be?

I'm on half a codeine three nights a week to get sleep so I don't thrash about and hurt my insides but that's it.

Thanks