Guinea pigs chewing fleece... & odor????

I decided to try fleece as the bedding for my guinea pigs. I just started yesterday. First I put down an old quilted mattress pad (I cut off the elastic) and then I put down a fleece blanket and secured it. It look so soft and comfy...but my guinea pigs have already chewed holes in the fleece...plus it looks gross with all the droppings and is starting to smell. What can I do abt the smell and the chewing? I know they like to chew but I can't buy new fleece every day. Any suggestions???