Caring for a Three Legged Dog or Cat

Hi all.  My dog Yoda was diagnosed with osteosarcoma about a week and a half ago and his front right leg was amputated 9 days ago.  He's been getting around great from the start - lucky us.   He's a probable Doberman mix (perhaps Doberman/Lab), about 6 years old.  I got him 3 years ago from the Humane Society.  The meds gave him a lot of anxiety for the first two days after he came home (4 days after the surgery) and he was vocalizing alot (Wow, that was only two days??  Sure didn't feel like it). 

I have two remaining concerns, though, and I'll probably post to the "ask a vet" forum too.  From the beginning his bowel movements have been really far apart - 24 to 36 hours and more towards the 36.  I'm used to him pooping twice a day, occasionally even three.  I understand that after anesthesia and while on Fenytal, constipation isn't unusual.  I was told once the Fenytal patch was off, the constipation should clear up. It's been four days without the patch and I haven't seen a change.  I called in again and they said to try giving him chicken and rice (I've been adding water too).  I started him on that last night, and, so far, no change.

On top of this, probably making me more anxious about how long this constipation is lasting, is that he's been having brief episodes where he cries out/whines in pain - I'm pretty sure.  This started 5 days after his surgery, the morning before he got the Fenytal patch off.  The first two or three times (that I know of) were early in the morning (like between 3am and 6am) while he was in bed.  I think every time has been while he's been in his bed.  They've gradually become more frequent.  Today it's happened three times.  He appears to be trying to shift his position in bed, then he seems to get stuck in a partial or full sit position and then he'll whine and shift for a bit like he wants to lie down but can't.  Finally he will, usually with a groan and/or whine and then he'll just stay down.  He's just on Rimadyl right now.  Maybe the pain is from the constipation?

By the way, maybe I have three concerns really, is it still normal for him to be lethargic?  It's 9 days after the surgery.  Comparatively, he didn't rest that much the first few days he was home, because he was so anxious.  Mabye he's making up for lost time?

I will try again to get new advice from the vet school where he's being treated, but the  last couple times I called, getting answers was like pulling teeth.  And, maybe I am over-reacting, because his appetite is good, he goes outside to do or attempt his business and gets around fine, urination seems normal, and his pain (if that's what it is) seems brief.  He lays on his incision most of the time, by the way, so it's hard to imagine that it's a painful area.

Okay, does this sound familiar to anyone?  Meanwhile I'm going to keep searching the site for more helpful info.  Thanks to everyone for their contributions, especially Jerry and his pawrents, of course!