dehydrated elderly rat

Question
My rat Sammy is 2 years and 10 months old. He has a large tumor (about the size of a small mandarin orange) that has a scab on it. He is also very paralyzed in his back legs and can't walk anymore. He is also very skinny and bony. He was better and eating yesterday, but only soft foods. Today he won't eat or drink at all and is very lethargic. His eyes are squinted and he keeps leaning his head to one side. I think hes dehydrated because when I pull his skin it doesn't go back down. What should I do? I also have a rat named Tony (same age as Sammy) who has what we thought was a tumor for a few months. Now it has a head and scab so I thought at first maybe it was really just an abscess but then I thought maybe his tumor had abscessed. It is the size of a tiny bean and hasn't grown at all. What do you think it is? Thank you.

Answer
your old boy may have kidney disease.  Try to offer him baby foods.  Have you tried that at all?

Also, if he has had this lump for months and it hasnt drained until now, its probably a tumor that has abscessed.  he doesnt sound healthy enough to have it removed. but I do suggest a few weeks of antibiotics to keep him from getting septic on you.  
Can he use his front paws to grasp anything?