Ozzy has been licking his paw for a couple of days and on closer inspection he seems to have a swollen toe. The swelling is very uniform and does not have any redness or goo coming out of it so I dont think its a sting or infected in anyway.

It isnt affecting his walking - he is still very bouncy, but he wont let me touch it and he is licking it quite a lot at night time.
What could this be?
I think he might have fallen or knocked himself.

How should I treat this?

At the vets, could be a grass seed or an infection. One of my clients dogs has a similar thing at the moment and the vet pulled a huge grass seed from under his nail

Worth getting it checked out. He might have something in there or it might be an infection, or it might be just one of those things!

Soli went in for a swelling on the side of her toe knuckle joint (by the wrist) last November - had it x-rayed, the vet thought it was bone cancer so took the whole toe off and sent it away, but it turned out to be some sort of inflammation of the ligament/tendon. No obvious cause and not sure what it was, and she's not had any problems since (a little lame sometimes but I wonder if that might be phantom pain from the missing toe).