Thank you for your query on Healthcare Magic.
This lump under the skin may me an abscess
which could be due to secondary infection of the bite wound with a bacteria.
First I advise you to seek medical attention regarding vaccination
against rabies as the dog was not up to date for anti rabies vaccination.
How is the dog health right now?
If the dog is healthy now, then nothing to worry as a healthy dog after 10 days of the bite indicate that it is not carrying rabies virus
But I advise you to consult your Physician regarding the anti rabies vaccination and wound management.
Hope I have answered your query.