Dear Cheryl,
Although a well,cared for rabbit can live up to 15 years, most only make it to 6 or 8 so your boy is an older guy. At this point the only ting the ER vet is going to do is hydrate him with subQ fluids and script him an antibiotic.As you say given his age it may not be fair to put him through such an ordeal. However, he is your baby and only you can make life or death decisions for him.Is he suffering? Is his quality of life diminished? How long will he have if he gets over this issue?
The best thing to do would be to have him seen and find out what his vitals are and if the attending veterinarian thinks he can be helped and then make your decision at that time. I can see that you love this boy and only want what is best for him. Follow your heart and you will make the right decision.
If I can help in any way at all or you just want to discuss this further - I will always be here for you.
Sincerest best wishes,
Terri