Mysterious lump on lorikeet

[Tiana's chickens]

2 days ago a Rainbow Lorikeet came into my care. She has a lump near/around her vent, the lump has looked the same for a good year atleast, hasn't grown apparently.
I have a couple ideas of what it might be but I'm not sure and would like some expert opinions.
Firstly it might just be a fatty lump (I forget the professional name for this) but she's probably been a little over fed and the cage she was in was small so probably not enough exercise either causing her to be overweight.
Secondly it could be a tumour (I really hope not ) she's about 12 years old.
Thirdly it could be some sort of prolapse. She's laid a lot of eggs in the past.
Or The lump could be something else I haven't thought of, I need some help in figuring this out so I can treat it.
Here are some photos of the lorikeets rear, although the lump looks smaller in photos and her feathers hide it a bit. It's atleast the size of a human eye
(Also just so yas know, I will trim her overgrown nails very soon and I also have an aviary she will be moving into soon for more space)

 

[JaeG]

Poor thing - sounds like she's come to the right place - your house! The only other thing I can think of would be a cyst. Does it seem to be tender?

I found this article:
https://www.petcha.com/lumps-tumors-in-birds/

 

[Tiana's chickens]

Thank you, I haven't actually touched it, she's a little anxious since moving to a new home. I'll have a feel next time I'm out there. Thank you for the article, much appreciated

 

[theoldchick]

Could be a lipoma but a Vet exam is the only way to be sure.