The baby food is just because its high protein. If she is eating normally then you don't have to switch. Baby food helps if they are eating but not as much as they should. It gets more protein into their system. You should probably keep her segregated for two weeks after she stops showing signs of infection. Keep her on the antibiotics the whole time. If she is showing improvement this fast then she will probably be fine, but you dont want to put her in with the rest of the flock while she may still be contagious.