Oh what a thing, havent had it with hens, but a few years ago my pregnant dog her paw swelled up so I used a needle and opened it out squessed and a ear of corn/rye popped out. These have needle sharpness when dried out, washed the paw out with salt water followed by hydriation preoxide ( used by vets you can buy at chemist for 99p) cleared up no problem.
Is your hen outside could she have picked up something like it?
Hydrogen Peroxide ( spelling corrected) at 6% will burn out any bad matter it foams up, I use it on us as well instead of iodine. It can tingle but nothing goes sepitic afterwards.
