I don't like how the swelling is also affecting his eye socket. That's approaching dangerous territory there. Especially if the swelling is still increasing.
What is Polter eating? Is this possibly a rodent bite?
Is this bioactive soil one you purchased? Or did you collect it?
I worry that if this isn't a pushing injury, this could be a bacterial or fungal infection which definitely would need medical intervention
Edit: Also! How long has this swelling been happening? How long has he been in iso? Some people call a week a couple of days... Some mean 2 days. Lol