Where and how are you checking your temps? Surface temps? Ambient temps? How are you regulating them? Do you have a thermostat, rheostat or dimmer controlling your lamps?
I would offer hides on BOTH ends of the tank. A warm and a cool hide.
As Slim said, lamps destroy your humidity, but this is easily fixed with extra misting or covering part of the top of the cage with aluminum foil, wax paper or a damp towel.
You say you're using "natural shavings". Aspen? Pine? Cedar? Cypress? Other? There are lots of different types of shavings and they are not all created equal. Pine and especially cedar are toxic to reptiles.
Ball pythons, even when established f/t feeders can and often do decide they will only eat live sometimes. 4 weeks isn't long for a ball to go without food, at least a healthy ball that isn't losing drastic amounts of weight. I certainly wouldn't resort to assist feeding yet. Assist feeding should only be used as last resort and it should only be done by a reptile vet or an experienced keeper. If you don't know what you're doing you can cause far more harm than good.