Or..... It's because the flesh has released or is partially released from the skeleton but still allowing the head to inflate, same way chalice or favias do, makes them look like a blob of jelly, I believe it's from damage to the individual head?¿
It has been that way now for almost a month now and does not seem to seperating from the skeleton in anyway... will keep my eye on it and see how it progress . Will post more pics as things develop