My bunny has randomly been doing a head movement and I dont know if its something to be worried about. Ive uploaded a video of it here : https://youtu.be/H_vPAYQ7Dw8
Those kind of head movements can sometimes indicate a problem in the bunny's mouth. It could be something as simple as a piece of hay stuck in their teeth, or it could be a dental problem such as molar spurs causing irritation and soreness to the inside of the mouth. If it is a dental issue, you may also see other symptoms such as changes in eating behavior and food selection, drooling, chewing slowly, dropping food from the mouth, lack of appetite, mushy poop. http://www.medirabbit.com/EN/Dental_diseases/Differential/D_problems1.htm http://wildpro.twycrosszoo.org/S/00dis/Miscellaneous/AcquiredMolarAbnRabbits.htm
If the behavior continues for more than a day or two, or your bun stops eating, I would get an appointment with a good rabbit vet right away, immediately if your bun stops eating. Make sure a thorough dental exam is done. It would also be good to make sure the ears are checked in case it's the ear canal causing the discomfort and not the mouth.