my hamster died due to unknown cause, the following details is describe the day before my hamster die:

day 1: there is something on his left eye, like he had a irritation on it. The eye cannot be open. So, I take a warm wet tissue to clean the eye. I repeat it several times. He go to sleep.

day 2: there is blood under his eyes, I think he scratch it hard and make it bleeding. He sleep to much and look weak.

day 3: I took him to the veterinary and the vet give him a injection of antibiotic. After the injection, he sleep all day long. Sometimes I woke him up to eat.

day 4: he still sleeping, and I see his breathing fast. I woke him to eat something, but he is too sleepy.. so he doesn’t eat much.

day 5: he didn’t even woke when I try to woke him, so I take him and try to give a drink. He couldn’t open his mouth. Only on the right side of his mouth is open to receive the water. Cannot open his eyes, and his ears are close down. He drink a little. Not later than that, he died.

So, what is this all about? What was the diseases my hamster had? If there is any prevention for this diseases?