Hi, sjmc. We had a springer, Priscilla (close to 15 years of age), with a similar problem. They never did diagnose her other than to find on xray a vague spot that looked like a mass way back in her sinuses. It would have meant surgically drilling through bone to biopsy, so we just let it be.
The bad news: Priscilla finally passed from the consequences of what was probably a nasal tumor. I won't lie to you--it was traumatic. The nosebleeds got worse and one day we knew it was her time. We'd made an appointment to see the vet, but the tumor burst before then and she bled out peacefully in the backyard. We put in an emergency call to the vet when it started and the vet was able to make it to the house a few minutes later to help Priscilla to the bridge...but by then, she was pretty much gone anyway.
The good news: it did not seem particularly painful for Priscilla. In fact, I felt, watching her, that it was much more traumatic for us than for her. She seemed very calm and accepting of what was happening. And she was such an independent soul and loved life so much that I doubt she would have had it any other way--spending her last moments under her favorite bushes with her favorite people.
I know that's not a happy ending to the story--and it may not happen for your dog. But I wished at the time that someone had warned me it might play out that way...and so I'll share the story with you.
that it doesn't come to that!
Are you sure she doesn't have a grass awn stuck up there somewhere? The symptoms can be similar to what you're describing--for a long time, that's what we thought Priscilla might be suffering from.