Hello, congrats and WELCOME
!
I don't know a whole lot about fleas, bc we don't have a big problem w/ them here, but I know someone will help you.
As for the vax area - this is not uncommon, but unfortunate. Sometimes at the spot of a shot (esp. rabies), a bare or crusty area will develop - and the hair may or may not grow back there (my Wylie's did not). Is the bump "spreading outward" or more like swelling up away from the skin? Is the hair gone?
My Vet Derm did tell me that if/when this happens to a dog, it can be much worse the next time - ie, a bigger bump, a bigger area...and that was not great to hear. She said that for small dogs who have this vasculitis reaction, she recommends not giving the entire vaccine, but it's tough to find a vet who will agree with that, ususally.