I know people are going to tell you on here to do all kind of stuff to make sure prey is warm and what not but in my opinion you should try a live mouse immediately.. If the snake isn't showing signs of being sick otherwise... That snake has lost almost 50% of its bodyweight and thats never good. What size tank are you keeping it in? As far as a live feeding goes, you buy the mouse and drop it in.. They will do the rest... You can just watch the mouse to make sure it doesn't bite into the snake and give it something to bite on but I have never run into this issue after MULTIPLE, MULTIPLE live feedings...