Girl in my sophomore class, so embarrassed?

I teach sophomore & senior classes (high school). I have a girl in my sophomore class that recently had a little accident with her period. It leaked on the seat & her skirt was stained. No one noticed since she did not get up from her seat all class. When the bell rang, she just stayed in her seat. I walked over to her and she started to cry. I gave bent down and asked her what was wrong. She merely just stood up, sobbing. I saw the seat covered in blood, and told her it was totally fine, and she doesn't need to be upset about it. She's about 16 years old. I didn't have a jacket to give her, but I walked her down to the nurse & stood behind her so no one could see her skirt. She thanked me and I went back to my next class. Then today, she came in to class and couldn't even make eye contact with me, she was still so embarrassed. How do I tell her she doesn't need to be, and comfort her? I am fairly new to teaching, and am only 24 years old. This is all so new to me!!