My eyelash crested gecko won't eat, why?

I've had her for about a year now. She's been losing weight. Her tail is all rigid. I was looking up what the problem could be and dehydration was one. I sprayed all around her last night and she drank a ton. And poor calcium was the other thing I found. Since I wasn't dusting her crickets recently. But i'm trying to get her to eat crickets covered in dust and she constantly backs a way from them. What should I do?