my rat is sick!

Question
i have a almost two year old black and white female rat. she has lost weight to the point i can feel her ribs and spine, she barely eats,and is weak.she sleeps a lot. her breathing is very heavy at times, any clue as to what is causing it? the other female "brown" is fine and in same cage,

Answer
Well she definitely doesn't feel good. As she shown any other signs of illness? I'd recommend offering her some soft, palatable foods.. baby food, canned cat/dog food, soft cooked veggies and mashed up fruit (sparingly on the fruit though-- too much can give her runny poo). If she has shown any other symptoms, let me know what they are, and I can give you some idea what is going on with her.