Is this bird in an aviary? Maybe its mate or an parrot in the next flight got it on the wire.
If in a cage, what type of perches? 99% of foot problems with pet birds is the unsuitable perches. I am not even going to ask if you have plastic or grit perches *shudder*Throw the ones that came with the cage away and get some branches from a willow or fruit tree. It will give the bird something to chew on too, Pennants love to chew. Renew when worn.
If the skin is broken dab some antiseptic on twice a day. If no improvement in a couple of days get some professional help, if not now.



