Hi Scott here. It is impossible to diagnose something like that over the inter net. However, there is a very common problem that can present that way, it is a tooth abscess. When the 4th upper premolar has a root abscess, dogs develop a swelling under the eye, right over that little point of bone. Other possibilities might be a growth,cyst or small foreign body. If you look into the mouth and count to the 4th tooth behind the K9, if part of it is missing or you see a dark spot it may be that tooth. The first upper molar can also cause this problem. Just like us, a dogs tooth can be abscessed and look normal as well.
It may be nothing at all...and tooth abscess are not always obviously painful in dogs. I would make an appointment ASAP to make certain it is not a tooth, and that it is nothing to worry about.
Maybe she just bumped it but I would have a vet check it because tooth abscesses can cause problems in the body elsewhere if that is what it is....
I hope you are not disappointed that I can not tell you what it is, if I did that I would be full of hot air and it would be unprofessional. I can tell you that something like that should be checked, because it sometimes is something like an abscess.
Your correct, it is impossible to diagnose things online. But that tooth does connect to a sinus and that is why you see a bump if there is pressure. If pus gets encapsulated it can even feel like a little pea. Sometimes it is just puffy.
Maybe she has a generalized facial swelling from the allergies and the ears, and it is more noticeable now. Maybe she has been rubbing her face as many dogs with allergies do..
I would still get it checked. Did you look at her teeth? Especially do so if you have ever given her bones or she has accidentally received bones. It is an extremely common vet finding.