is everyone who is dying in pain? wondering if i did the right thing,

Hi everyone. I have a question about a situation that pops into my mind occasionally. I had only been a nurse for about 2 years in med surg. At the first hospital I worked at we sometimes had hospice patients but not often. I learned that they are there to keep them comfortable etc...Ok, well I moved and got a job as agency on a neuro floor where there were never hospice patients. Well, we had a patient, a young man who was dying of AIDS. He wasn't "in hospice". His Doctor didn't seem too sympathetic to me by the way (the family was not educated, charity, two girlfriend that came to visit, family drama etc, you get the picture).
But he was essentially there to die. His liver was beginning to fail. The doctor made it clear that there was nothing they could do. Though he didn't have a regular regimen to make him comfortable, he did have some ativan or xanax ordered. I don't remember exactly which one. Nothing for pain though. And noone ever gave him the anxiety med. And of course he was not "there" and didn't talk or ever ask for anything.
Well when I had him as a patient, I asked the doctor if we should give him something for pain to make him more comfortable because I was thinking about the hospice patients I had at the other hospital. To me, he seemed uncomfortable and agitated. Though he was moaning or acting like it was pain exactly and the doctor said "why, is he in pain" and I explained what I thought. He didn't order anything. But to me, he is dying. I mean really close I think. Wouldn't you think he would be in pain? I mean, serious question, do you all think if you are dying that you are in pain? I would think so.
Anyway, I had him a couple of days later and no nurses ever gave him anything and again to me he seemed agitated and uncomfortable but not moaning or writhing or anything. I think because maybe they were scared because of his liver. The mother and family were of course upset and said can't you give him something, so they thought he was uncomfortable, and they know him better than me of course. So I gave him the dose of xanax or the ativan that was ordered. (I don't really remember which one, it was a long time ago and I haven't been working for over a year). Well guess what? That night he died.
Well the next day the nurses, remember I was new at this hospital and we all know how nurses can be to one another, and one nurse insinuated that he died because of what I gave him and said something like well duh the medication is excreted through the liver mostly not the kidneys like I was stupid for giving that to him (like she looked it up and was looking for something, and remember his liver was failing). No one ever said anything outright though, but I am thinking "well good, he is not suffering anymore and everyone was waiting for him to die and were relieved." The med did make him seem less agitated the day I had him. I truly feel like I did the right thing but it often pops into my mind but...
I guess the question I mostly want answered is, do you all think that if someone is dying that they are automatically uncomfortable and in pain even if it doesn't seem blatantly obvious. I mean doesn't it hurt when a persons organs are failing? I really don't know but would think so. Did I do the right thing?