It's a bit runny, but I don't see worms, and it is a good color. Chicken poo has a wide variation of normal. Your bird's poo may be a normal dropping (see chart below).
However, with the history of antibiotic use, if the bird is consistently giving runny poo, then you should do something. With the history of antibiotics, I suspicion gut imbalances. (Although worms is always a potential with runny poo).
If you've been giving antibiotics, don't give more antibiotics for diarrhea. Antibiotics also attack the good bacteria in the gut creating an imbalance in gut flora that will cause diarrhea.
I suggest giving your bird some pro-biotics, like yogurt or a powder formula in the water.
Also give it ACV (apple cider vinegar, raw, unpasturized, with the mother, in plastic water carrier only) which helps feed the good bacteria in the gut.
That should help clear up the runs.
If not, then you can go back to disease...btw...why were you giving antibiotics? Wry neck is a vitamin deficiency not a bacterial disease.
Was your bird sick with something else?
LofMc
here is also a good poo chart for what is normal and what is abnormal:
http://www.the-chicken-chick.com/2012/02/whats-scoop-on-chicken-poop-digestive.html