Hello and thanks for posting,

I am sorry to hear about your dad's situation. I can't really comment on the stent expanding, as we are not directly involved in his day to day clinical care. Sometimes, it can be that small nerve endings around the stent area may be irritated. 

If the morphine is not controlling the pain, then do make contact with whoever prescribed it, such as his GP or community team.

He may need the dose increasing, or another different painkiller added in as well. Whenever anyone is on regular morphine, it helps if an anti sickness medication is also prescribed, as it can cause nausea. Morphine can also cause constipation in some patients. It can be given as a slow release tablet, and there are also long release skin patches of other similar painkillers. 

We have some information here about painkillers,

www.cancerresearchuk.org/.../types-of-painkillers

I hope that this helps,

Kind regards,

Vanda