Ancona limping with a swollen toe...

Just noticed my 6 month old Ancona is limping. After examining her foot it seems like one of her toes is swollen. She also has some feather loss on her back with skin looking a little scaly. Don't think it's anywhere rooster will hold on to while mounting. I have tylan 50 that I gave two of my girls in the summer for a swollen eye. Was wondering if I should just giver her a dose. Not sure how to treat her swollen toe or her skin. Any advice will be greatly appreciated.