My friend's eye, just one, has been bothering her for awhile, like causing her pain. She went to her doctor and he said that she just needed to go back to an old prescription, which she did and her vision was worse, so that didn't work. For the last few days her eye has been red and still painful. This morning she woke up and she couldn't see anything, like her eye wouldn't open to light and it is red around her pupil. Any ideas what's wrong? And how serious is it?