grape sized knot below dogs ear

Question
We own a small corgi, she developed a small grape-sized knot under her left ear, it seemed like overnight, we thought it was some kind of allergic reaction at first, but the size has not been reduced. It doesn't seem to be causing her any pain, it is hard as a rock, but she doesn't whine or scratch at it. What could this be.

Answer
Hello Scott;
There are a number of things this could be...from a Cyst to a inflamed pore, to a bite or a scratch that is now full and hard with fluid...
The best thing to do is take her to the Vet.
This way all things possible can be ruled out.
We don't want to jump to conclusions, as there are many more possibilities...and some are not so great.
So, make an appointment, and have her checked.
Chances are the swelling will go down on its own, but, the Vet may want to test it and or lance it.
So, do take her in.
I appreciate all requests, and do try to come up with solutions, but, somethings take "Testing".

Please feel free to contact me again, and let me know how she is doing!

I appreciate all "feedback" and any other questions, I am able to help out with.

I also would love a rating if possible.
Thanks again,
And I look forward to hearing back from you,
Best regards,
Melissa