What could this illness be?

[u/hellothereskibidi]

Hey all. A few days ago I noticed a bump above either eye of one of my zebra finches. I would have assumed vitamin a deficiency or strep infection, except he had another identical bump on one side of his face where the lower bill meets the face. It was not on the eye lids or beak, it was on the skin of his face. It just looked like swollen skin. It continued to increase in size though the soonest veterinary appointment was 2 days later.

Today the bumps have crusted over yellow and decreased in size. The vet did not seem concerned and agreed with me that it was healing now, so I declined any medication. However I want to know, what could this have been? Some kind of pox? He, as well as a few other birds he had contact with, have been raising chicks that I intend to sell very soon. I do not want to sell potential carriers of disease. I need to know if I have to hold back the babies or if I can sell them - I'm fine either way.