My banana ball python keeps rubbing his head hard against the side and his hide?

[Ballpython2000]

My banana ball python keeps moving most of the time and he isnt in shed and he is doing a little bit of head wobbling by the looks of things and he is also rubbing and even seen him bang his head sometimes against walls and the top of his tank and cant see any mites or anything. any help would be great as i am quite worried

[cletus]

How is your husbandry? Temps, humidity etc... How big is the snake and what size enclosure?

[Ballpython2000]

he is in a 18 litre rub and the snake is only 1 and a half foot his hot side is around 88-90 degrees and cold side is around 80 degrees and humidity is about 50%.