Yesterday, one of my about 2 months old chicken has been stuck between 2 wooden objects for several hours. After I free it, I noticed black stuff on the skin which is probably blood, and I saw several oval shape black substance under the skin that moves around whenever I try to move it. What are those oval shape substance? Today, I saw the skin turned green around the area that is black and red in color( the same area where I found the black substance and the black stuff on the skin). I am not sure how long it have that injury, but I think it is less than 24 hours after I free it. What should I do, asides from using antibiotic ointment on the skin?