Well, I don't really have any advice, or anything to add - But will post anyway :P
I have a similar problem. To make it short - I first complained of loss of hearing and ear fullness, my Gp thought it was just some fluid build up... so prescribed Trinalin Repetabs... twice to no avail.... then sent me to an ENT. The ENT spent a few mins with me, looked in my ear, and sent me for hearing tests. He found pressure and the sort in the left ear, and decided to place a tube in the left ear only. Boy was that a mistake!!! (you should count yourself lucky that you never had one
After the tube I developed severe tinnitus, and horrible constant earaches - to go along with the fullness and pressure. I also had PND. I returned to the ENT and he ripped the tube out, saying it had "slipped out of place". He gave me Nasonex and told me to return if I had any more problems with my ear.
Well I went back to the GP and asked for a different ENT. Some good that was. He was a colleague of the first. He sent me for the hearing tests again, after i told him I had no problem with the hearing now, but with the pain and tinnitus. After getting the results he told me I have TMJ (DUH! I knew that) and that I needed to, and I quote, "Win the lottery and move to a warmer climate". The nerve of this guy... Then I went to a walk in clinic and the doctor there told me I have more fluid and ETD and to continue with the Nasonex and try Sudafed.... which is not helping either.
And thats where I am now. I know I have TMJ... I was told that when I was 19... arthritic changes... but it seems too coincidental that it all happened after a bad flu, fluid build up and the tube placement. My ears never bothered me before.
Anyway, just wanted to let you know you are not alone. I am still suffering... after two long years of this being drawn out... but I am managing it.
I think it may a combination of many things. The TMJ, the allergies, etc, and it is only now affecting you. Hopefully the splint will do its job... sometimes you have to go through a few different ones though to find the right one for you. Maybe ask about Nasonex as it is stronger than Flonase. And I would recommend irrigating with a saline solution before using a spray. Also, I believe if the tinnitus is a real issue for you, there are tinnitus maskers available... I don't know how well they work though. From my understanding they are devices worn in the ear to counteract the tinnitus.