veeeeery strange death

[Conas]

i fed all of my baby bp's a mouse 3 days ago. He killed and swallowed the little critter with no problems at all. Yesterday i noticed that the other python's post-meal bulge was nearly gone, but one was huge as before. I then realized that the snake was dead. For some reason, too, he had came back to his neck and bit himself and stayed like that while dying. On his belly, he had darkened skin between his tail and said mouse.

Have any of yall encountered this before? Was my snake sick or did the mouse kill him? All the other snakes are doing just fine. If anyone could please help me understand what may have happened, i would really appreciate it so it doesn't happen again. Thanx