Please help, my rats are sick

[Jenmf95]

Both of my female fancy rats are just over two years old and they both have lumps on their back ends suddenly, and one of the girls is missing hair on her back and is very lethargic, also she can’t seem to walk straight. They are both eating and drinking water.
I haven’t seen them in a couple weeks as they live with my boyfriend but they were fine last time I was visiting, and my boyfriend said he’s just recently noticed the lumps but they are quite large. I am terrified, they have both had perfect health since I brought them home as babies.
I want to take them to a Vet but I’m not financially able to take on any vet bills right now.
Can anyone give me advice on what I should do? :’( I can’t tell if they’re in pain and I want to make sure they are comfortable.

 

[Dena]

Can you post a video of how they are walking, and give the one who can't walk straight a cheerios, or something small to hold in her hands and eat. That way, lilspaz or someone can help identify what may be going on. Can you have your boyfriend hold the rat's sides to his ears like a rat phone and see if he can hear any noises? You can upload the video to YouTube, then copy and paste the link on here.