This is usually the result of temps being too cool or not enough calcium and vitamins in the diet. What temperatures are you keeping it at and what supplements do you use and how often? It may also be hooked on pinkies, try and add as much variety as possible to find something else it likes e.g. locusts, earthworms, superworms, dubia roaches, crickets...

The preferred my method of heating is with a low wattage heat bulb but many keepers use a mat under the tank connected to a thermostat. Plastic tanks are not the best and they don't hold heat very well and difficult to like. Although nocturnal, they need a photoperiod of 12 hours light and 12 hours darkness