My big girl Rosey, developed a lump on her nose like that. It turned out to be a sinus infection. I would wait a few days and see if the swelling goes down. If it doesnt, then try and gently feel it and see if it feels squishy like a blister. If so, you need to go to the vet and have them take a sample of the liquid with a needle. Thats whats my vet did and then had it cultured or whatever they do. Other than that, my boa seemed fine too. She ended up getting a shot every other day of Fortaz for a month and now she is fine but she still has a slight lump that the vet said might or might not go away with time. Good luck.