New rat behavior

Question
I HAVE TWO  FEMALE RATS THAT ARE 1 AND 1/2 YEARS OLD. RECENTLY ,ONE
OF THEM HAS BEGUN TO BEHAVE DIFFERENTLY . SHE DOESN'T SEEM TO WANT
TO STAY IN HER CAGE. SHE GNAWS AT THE CAGE AND RUNS AROUND TRYING
TO FIND A WAY OUT AND GENERALLY ACTS STRESSED. SHE ALSO SEEMS TO
BE LOSING WEIGHT??
WE BOUGHT A NEW AND MUCH BIGGER CAGE FOR THE TWO OF THEM BUT
THE BEHAVIOR HAS CONTINUED.
ALSO, SHE HAS A PATCH OF HAIR LOSS ON HER BODY. ITS BEEN THERE FOR
MONTHS AND HASN'T GOTTEN MUCH BIGGER BUT NO BETTER EITHER.
I HOPE YOU CAN HELP.
THANK YOU!

Answer
Have you noticed her breathing is labored or heavy (or rapid)? Is the bald patch slightly reddish, raised or crusty?

Rats that begin losing weight and act frantic sometimes aren't getting the oxygen they need, and it would be wise to have her looked at by a vet specializing in pocket pets to be sure she doesn't have a respiratory infection or isn't suffering from congestive heart failure. The bald patch could be due to ringworm or overgrooming, and overgrooming often occurs out of boredom. How often do your rats get out of their cage to play?