My husband got extremely constipated when we first got home from treatment - I bought a Fleet's enema at the drugstore and it helped enormously! Admittedly, I'm a nurse so I was comfortable giving it to him - but there are instructions on the box and he could probably do it himself. If the enema doesn't work, there are other things his doctor can prescribe.
We also switched to the fentanyl patch at the end of treatment because the short acting pain relievers (e.g. Lortab) were allowing his pain to spike when he hit the 4 hour mark. The patch has been awesome - can't say enough good things about it.
I'm still new to all of this and I'm sure many of the more "experienced others" will have more advice and experience to share.