Underbelly scabbed up and snake wont eat

[Riley]

A little over a month ago my ball python swallowed a piece of bedding with a mouse and I could tell it tore him up a little bit inside but he didnt seem too effected by it. After his most recent shed, his underbelly looked pretty torn up, I was guessing it was from the woodchip he swallowed and figured he would heal. Well it has been three weeks since he has eaten (usually eats once a week) and his belly has gotten MUCH worse, the part that was torn up now looks scabbed up. He seems hungry, but when a mouse goes near him he gets scared and tries to hide. I think he is affraid the mouse may harm him while he is injured. I tried feeding him frozen and he won't go for it. I have been putting coconut oil on the effected area and trying to feed him periodically, but I am beginning to worry. I also wondered if it was from my undertank heater so I have stopped using that. Can someone tell me what to do next? Is he okay to fast until he is healed?