Chick has a big lump

[Kallyroberts]

My baby chick has a lump! I noticed it for the 1st time tonight and it's about the size of a quarter on the right side of his neck/chest. I felt around it and it feels hard.
I tried taking some pics but they are not very good but please Dvise me as to what it is and what I should do.
Thanks!

 

[Angie16hearts]

I'm new to this but have 2 older girls and. 3 chicks. I believe it's crop is full. Meaning she filled her self up with food and should pass over night . I noticed it on mine and it seems to be full every night if they have had food. I think you can find a picture of a chickens body structure on internet that will explain more ... Good luck ! They are so precious