Gecko not eating

So I recently got a gecko and it’s tank has a source of light, heat mat warm damp on one side dry cool on other and so on. But my gecko started to regurgitate the mealworms and ever since hasn’t really eaten much. I’ve tried all different insects and foods but he just doesn’t seem interested. From both pics you can clearly see he has lost his colour but he has shedded fine and isn’t due another shed in a while HELP WHAT IS WRONG