My sussex has a lump

[chickenman10]

My light sussex chicken has a lump on her back and it is about 3 centimetres off her back i am worried all the others dont have it!!! what is it

she acts and interacts like evey1 else but i am just worried about this

is it a tumer please help!!!!

 

[emys]

If you could post a picture of it that would help. Also, how long has it been there? Is it getting larger or staying the same?