Massave Lump?

On my serian hamster

It is about the size of a grape, her skin under it is blueish grey, , its hard, feels kinda like a boiled egg, but i can move it around on her

It is on her chest between her arms. It seemed to appear over night because i noticed it for the first time yesterday

Do you think there could be some disease that shows different symptoms, because if you read my other question about my dwarf hamster, you know that she is having health issues also

I do a pretty good job at keeping their cages clean, they get fresh water daily or every 2 days. I have been kind of ignoring them the past couple of weeks since i got a cockatiel, and have been giving most of my attention to it the first few weeks i had it, but now im giving my hamsters the right amount of attention again, so...i just dont know what it is

Im trying to convince my parents to make me a vet appointment for them (they don't really like paying for a rodents vet bills) But, im paying for it, so (con't)

I have a four year old rat with the same thing. Between her front legs on her chest. I think it is a pocket of edema or a fatty tumor. She is very old and is losing her hair in patches, so thought it could be her thyroid. She has lived a good life so I will continue to take care of her the best I can, but, rats life expectancy is 2-3 years and maybe a bit more, so she's old and I can't see or afford paying a vet to tell me that.