I got a ball python almost a month ago and i can not get him to eat?

When i bought my ball python i was told that he eats once a week (every tuesday) and that he has been eating fuzzy mice. So i bought fuzzy mice to feed him (they are frozen/thawed) but he will not eat! I have tried every tuesday since I have had him and have tried many different feeding techniques. Now when he moves around it almost looks as if someone is pulling his skin out on his sides in some areas. Please help I am really worried that he is not eating and have no idea whats wrong