There are two things I have seen over the years with animals that swelled up RI and allergic reaction, in the case of the allergic reaction I recall those animals were on a wood type substrate, and once change onto something else the swelling went away, obviously if you use paper towel I would likely rule the second one out (well at least for allergic reaction to wood)
I would clean the cage out completely remove any possible residue of the product used for mite treatment and then I would make an appointment with an herp vet.