Sorry to be pedantic, but if a patient states that they have tinnitus it means they have abnormal sounds that they hear. There is no test to refute that a patient is hearing any particular sound. It is possible to match a particular frequency to what a patient states they are hearing, but you cannot tell them they don't have tinnitus. Where the tinnitus is being generated is another matter entirely.
The symptoms, at least initially, match what I know to be similar to otolith caused irritation. Tinnitus tone and volume can be changed by pressure over the scalp, mastoid, external auditory meatus and jaw pressure / alignment including Cx musculature - but the previously mentioned structures do not permanently change tinnitus. Therefore treatment to the Cx may alter symptoms of tinnitus, motion sickness and nausea in the short term partially due to Cx baroreceptor changes as musculature temprarily relaxes. Balance is complex, as you know, with many inputs to the brain having to match or disparate input causes delayed neural processing, a lag, resulting in the nausea, motion sickness etc. Postural change then occurs in the postural muscles in an attempt to stabilise input to the brain by reducing stimulus that causes symptoms. A learned response then occurs along with increased muscle tone that creates increased activity and then muscle shortening from the increased tone. Just some more thoughts to add into the discussion mix before I get some sleep!