Why believe in something you cannot see, right?
Not all doctors know how to diagnose or treat these conditions.
It is easy to say "everything is OK" especially if patients cannot prove their symptoms (some holes are not visible on CT, nystagmus is present only with vertigo, not with subjective dizziness, not with derealisation or a loss of focus).
All of these third windows' symptoms are similar and all of them can cause auditory or vestibular disturbances (and some of them pressure headache, visual disturbances, cognitive impairment) and it is difficult to fugure out what is what.
If after a month and a half of "head elevated, no straining etc" the symptoms don't reduce on their own, and if vestibular symptoms are severe, doctors might have to do a surgery, and the surgery does not guarantee a permanent fix even if they know where the hole is, some people later do 5-6 surgeries if the symptoms reoccur due to another pressure altering event, acoustic trauma, hit in the head etc.
By the way there are some German studies which showed 30% of patients with SSHL had PLF confirmed at the exploratory surgery (patching of the oval/round window) but then again, what with these 70%? They underwent unnecessary surgery (It is possible some of them had a fistula which started healing but still).
And that is why I am saying if people have SSHL and/or weird vestibular symptoms etc which start immediately or gradually after a severe acoustic trauma, scuba diving, airplane barotrauma, upper respiratory infection, weightlifting, excessive straining, hit in the head etc, and their doctors don't see anything, they should try sleeping in a reclined position and restrain from anything that can slow down spontaneous healing of a potential tear/rupture.