what's meaning of a blood lump under turtle's tail?

Question

the size of lump is about a nickel large, couple days later turtle died.

Answer 1

A 'prolapse' is an organ that has slipped out of the reptiles cloaca. A lot of organs can slip out like that- usually as part of an illness, injury, diet problem, or internal blockage.

If the organ does not retract within a few minutes, it should be seen by a vet quickly- it can be a BIG problem and is often fatal.

Answer 2

Sounds like a prolapsed rectum. Could have happened from parasites or other disease.