It could be conjunctivitis ,pink eye, and she will need an anti biotic ..or it may be allergies, we have this problem where I live along with scratchy throat, dry cough and fatigue, we believe its from environmental factors .
She could also have a blocked tear duct. Or pink eye. Call your doc AND wash your hands. Pink eye is really contagious! My guess is it is one of those two things. They prescribe a simple eye drop for it and some docs will even just do it over the phone as this is so simple to treat and common. So, call and check on this.
My allergies affect my eyes but in the way most allergies do, a 'histimine' way in that they itch and water and swell. People with allergies affecting their eyes typically are rubbing and trying to itch them. Is she doing that? If so, there is an over the counter allergy eye drop that works pretty well. It takes care of a histimine response due to allergies. But the crusting isn't common with that.
Well, good luck.