Littlewren
We all react differently to anesthetic and pain killers etc. Depending on the type of surgery he has been bashed about, possibly been semi inclined upside down for a few hours, pumped full of gas and had bits taken. Being in a hospital ward is not the best place for recovery.
You should see a vast improvement in the next few days , keep him hydrated and if he hasn't already passed a motion make sure he doesn't get constipation. Once his bodily functions get back to normal his appetite will return to normal as well.
Some painkillers can cause constipation. I don't recall being in too much pain and I kept refusing painkillers.
Always difficult seeing a loved one not at thier best , but in the next few days you should see him getting better. Take it easy but not too easy, he needs to keep mobile but no running marathons.
If you are worried about him call for medical advice , we keep being told the NHS is open for us.
Hope all goes well.
Thanks Chris