how long does antibiotics take to work

Hi everyone on tuesday i found my barred rock hen wobbly on her legs,weak,runny poo, That night i treated her with antibiotics in the mouth with sulfa 3 which treats bacterial,respiratory diesease,chlamydia,and cocci. Wednesday morning she was up walking bit stiff legged,eatting and drinking seemed to have normal poo. We did have a buff orpington rooster which was alot bigger then my barred rock, He use to attack her jump on her,peck and chase her. So i'm thinking the buff orpington rooster which we culled had injured her somehow cause i've never seen antibiotics work so fast.
Should i continue with treatment or should i stop all other chickens are fine and my barred rock seems to be back to normal except the stiff legs which will take time to heal.