I'm sorry to hear that you are having difficulty with your snake.
I realize that you saved up your money and bought the snake---the equipment needed to properly care for a ball python can be a lot more expensive than the snake itself. Describe your setup and heat sources so we can eliminate that as a potential cause.
Ball Pythons won't eat well unless they are comfortable. Handling a ball python (at all) that is a problem eater is also a bad idea as it also stresses them out. Once the snake is firmly set on a steady routine is the best time to handle them.
Also, since the snake is from one of the Pet store chains...there is a small chance it has internal parasites or a defect that you have not spotted. This would require a trip to the Vet....like I said though-I think it is more likely the setup than a medical issue...