Thanks for all the support.
My daughter is devestated by it. His name was Thumper and he was a black lop eared bunny. Very friendly and affectionate. You could carry him all over, clip his nails, he would just hang out with you. He loved to be petted and shown attention. He was just Daisy's size and was not afraid of her at all. She would visit him in my daughter's room and they would hang out together.
I really don't get why he died. I am in shock. He has been fine. No diarhea, not sick. He's been himself, very happy & energetic. Ate well. Santa had brought him a 3 story bunny condo for Xmas...he was very happy.
My daughter was petting him before school. I heard him at about 10 am hopping around his cage. We went out for a couple of hours then came back. We were getting ready to go out again and I peeked into my daughter's room and found him already gone.
We took him to the vet to have him cremated. The vets office said to do a necropsy would be $200 - $1000 and it did not guarantee finding a cause so we decided not to do the necropsy..
I feel so bad he passed away by himself. I should've poked my head in there sooner.
This is really hard....