It's almost definitely an infection. It should be cleaned out properly and the pus and tested so the chameleon can be put on the correct antibiotic to kill it. Bacteria will likely be pseudomonas aerignosa.
It's a female jumbo jackson - with babies. I feel like the babies complicate things. Are these treatments safe for them? (She's almost 5 months.)
Also, her eating has slowed down.
It would depend on the antibiotic. The stress of treatment is a consideration in a heavily gravid female. Not treating could have implications as well. Sorry to hear she is so young and gravid.
Hey everyone! I wanted to give an update for future cham owners to reference:
I took her to the vet. They used a 25 gauge needle and an upward wrist "flick" to open the bubble. The "puss" was pushed out and put on a slide. It is bacterial. The toe is being treated 2x a day by diluting a betadine solution (povidone-iodine) with water to make a "tea" looking solution. It's dabbed on toe. Then a triple antibiotic ointment is dabbed on afterwards. And she's good to go!
I also want to thank everyone for the helpful comments and directions.
I'm not a vet but these infections are sometimes hard to get rid of with only one treatment/clean out...so it may depend partly on the bacteria and also how well it was cleaned out or if it could spread. I'm thinking the topical might be the best option since she's gravid...but like I said...I'm not a vet.