Shouldn't drop below 75 at night, not 74 ish you need to find a way to increase temps also remember they are snakes from Africa. Need to heat 74 ish to 83 ish. Aslo try live sometimes snakes, especially Balls will not eat or will go off food for long periods of time. Try live and see if that gets her going. Its also winter normal for them to go off feed, you might try hibernating her, but if she is losing weight, that not a good idea till you have put more weight on her