is my chicken sick?

[danielab95]

my chick is about 9 weeks old it looks very fat and when is walks it looks like its waddling I'm not sure whats wrong with it but it keeps eating it is also quite slow when it runs compared to the others

 

[6 littleHens]

If you have it with adult chickens they may be jumping on him and chasing him.

 

[danielab95]

No all the rest of the chicks are the same age and I have two ducks that are the same age aswell I'm not to sure what's wrong with it I first thought it was over eating but now I'm not sure it runs some times too but it's more like its waddling fast