If you look at the St. John's Ambulance guidelines, ANY second degree burn requires medical attention. Obviously, that can be tempered with reality; a blister the size of a chocolate chip doesn't really require medical attention, but yours is waaaay past that.

You need to avoid infection, you need to deal with any infection you may already have, and you need to deal with the fact that improper care of the "egg" could lead to very extensive scarring.

Get thee to your GP or even your local hospital and take care of yourself, fer chrissakes.