Hi. My gerbil is about 3.5 years old. He has been very lazy lately. There is crust in his eyes and he can hardly open them. He is making a weird noise and I don't know if he is sick or dying. He does not eat or drink much any more and barley moves around. I don't know if he is cold or not because he is extremly afraid of humans and I don't want to disturb him. Can you tell me what is wrong?