Hello
If your pug has a tick on her ear you will notice it gets slowly bigger as it engorges. It will also have small legs near to site of attachment which move (you will see them wiggling). I think it is unlikely as you regularly use your Frontline. If it is a tick it will drop off naturally when it is fully engorged.
If it is a scab, I would be monitoring it carefully over the next few days. If it is growing or bleeding excessively have it checked at the vet. This could indicate a tumor (usually benign histiocytoma in such a young dog) Also if any more areas become scabbed or loose fur this could indicate a spreading skin infection. Or if she is scratching or rubbing it.
It is probably best not to bathe the scab or apply any creams/ointments until you know more about it.
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