Based upon what you have posted, it certainly is within the realm of possibility that you have experienced recent eustachian tube dysfunction following an upper respiratory illness like the flu. Eustachian tube dysfunction can be associated with dysequilibrium. Therefore I suspect that the eustachian tube problems have merely aggravated a preexistent problem.
Some individuals are highly susceptible to motion induced illness.
Some individuals get sick regularly when riding in the back seat of a car, others do not. Some cannot even think of riding a carnival ride while others are not even slightly bothered by the rotary motion of even the wildest ride. Often there is a great deal of psychological overlay present contributing to the experience of one who is highly susceptible to motion induced illness. This is usually based upon past experiences and a strong desire to avoid the illness - anxiety and anticipation therefore can potentiate or aggravate the problem. Many times an individual can adapt to activities that in the past may have triggered motion illness if they set their mind to it.