Stress does strange thing to the body. Especially if she is bearing the brunt on her own.<br />
Maybe help her out. You are old enough to do so. Think of what you can do to relieve some of her burden, and go for it.<br />
I know many people whom the stress has this effect on them too.. i've never known why but i think you don't have to worry, it's normal and happens to many people
That's tough. She has to seek help, stress is a killer too, ages you too.
Eating disorder maybe perhaps one in the past. bulimia is hard to get over.