my rhode island red just died and it sounds almost exactly like that. my fav chicken ( a silkie ) died yesterday not sure why but i am getting her autopsied to find out y.
i think your rir may have been egg-bound that is what happened to mine
Animals die and its not your fault. It just happens sometimes and it will happen again, so it becomes a life lesson when you set out to have livestock or pets. It never feels good but it does get easier to handle.