Rheumtoid arthritis, Scleritis, and now a chronic blocked ear

My wife has rheumatoid arthitis (16 years) and Scleritis in both eyes (2 years) - she takes a combination of steroids and methotrexate to control these conditions.
8 months ago after a plane flight my wife's right ear became blocked, and has never been 100% correct since. Most days her ear will suddenly block up, and her voice sounds like a she has a blocked nose. This normally occurs daily at random times when she gets tired and lasts hours. Normally she wakes up in the morning fine. Theres no ear pain or hearing loss. No wax, no jaw popping. Its just a feeling of a ear that wont pop. It goes away eventually. All the usual tecniques for un-popping a blocked ear that are well documented do not work. It seems linked to fatigue, and I suspect linked to her rheumatoid arthritis somehow.
Ear specialists say there is no wax or blockage, the Eustachian tubes are clear. Tests for growths are negative.

Could this be arthitis related? Can anyone offer some hope/idea apart from go and see more sceptical specialists?
All the usual tests have been done, but most often ear specialists are not arthitis specialists, so I wonder if there is a link being missed?
A hearing test has revealed no loss of hearing - it is something that just occurs later in the day when she is tired from work, and affects one ear only. She says her voice sounds funny to her when she speaks, and I notice immediately as she sounds very 'nasally'. I am worried that there might be an underlying progressive illness which if left undiagnosed will get worse, but the ear specialist dont seem to be taking it very seriously - probably because its not a conventional problem that they can diagnose?

I will also put this message on the ear/nose/throat forum as well to see if this helps.