Your temps are off. Typically balls will not eat if too hot or too cool. small snakes like your really need a proper gradient. and often do better with slightly lower hot spots. The big concern is 87ºF is WAY too hot for a cool end temp!! 80ºF is correct and 78-82º a fair working range. 90ºF is ok smaller snakes often do better a touch cooler 88-90ºF but it is the cool end temp that is concerning.