so very sorry had some real life rat emergencies to take care of so I missed your post.
Sudden and severe inner ear infection, could be head tilt, circling, falling over, nystagmus of the eyes (where they twitch).
In these cases antibiotics and steroids if possible are needed ASAP. If you cannot get steroids, giving NSAID's for a few days to combat the discomfort is better than nothing (Metacam/meloxicam or infant liquid ibuprofen)
Otis media is inflammation of the middle ear
Otis interna/labyrinthitis is inflammation of the inner ear and structures.
Otitis media and interna often develop when bacteria, such as Mycoplasma pulmonis, Streptobacillus moniliformis, or Psuedomonas aeruginosa, and viruses travel from the naso-pharynx through the Eustachian tubes to involve the lining of the ear. As the infection progresses to involve the labyrinth structure of the inner ear, inflammation to the vestibular nerve and swelling of the surrounding tissues results in “torticollis” or a tilting of the head. This tilting is most often directed towards the side of the affected ear. It is sometimes referred to as “Head Tilt”