Gotcha, I guess I didn't read that as 7 total injections the first time around. 7 doses over 21 days is correct.
If they already sent a sample of the mass off to the lab did they identify what strain of bacteria is present? If the lump turns out to be puss of some sort it will likely need to be surgically removed. Reptilian puss is unlike mammalian puss in that it is a solid instead of liquid.
Was just double checking that your vet wasn't throwing antibiotics at a problem without knowing for sure that it was a bacterial infection. Many seem to follow the shoot first, ask questions later when treating reptiles unfortunately. Sounds like you're doing everything you should! Keep us posted!