[Brity858]

 

[JoanneF]

It could be anything - a bite, a sting, an infection from a tiny puncture - if it doesn't go away after a couple of days, or if it gets worse, see your vet.

 

[emeraldecho]

In your shoes, I'd give it a salt water soak (which acts as a general antiseptic and draws out infections), keep it clean, and wait and see. If it hasn't improved in a couple days, a call to the vet is in order.